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shxtigraphy at the two sites, measurements near Austin cannot be considered to be <br />analogous to what would be measured at the proposed quarry location. Yet the report <br />states they are equivalent. This is cleazly a conjecture that has no supporting evidence. <br />2) Data analysis procedures are questionable, producing regression curves that do <br />not fit measured data, and no statistical analysis of ezpected error, confidence levels, <br />or significance of fit are provided. <br />Measurements of ground velocity versus distance from each piece of equipment <br />are displayed in Figure 4 of the Revey report. There is a scatter in measured values for <br />each piece of equipment at a fixed distance that is likely due to the lack of repeatability of <br />the activity of the equipment during testing. No description of the activity is provided. <br />The photo shows a dozer pushing dirt, yet the dozer will be used to rip lithified sandstone <br />and shale bedrock at the proposed quarry site. These are not equivalent activities. <br />Likewise measurements over a range of distance for each piece of equipment exhibit <br />inconsistent trends. This could be due to variation in sensor coupling as well as lack of <br />repeatability of the source. Regression lines shown in this figure do not appear to fit the <br />measured data. Performing a regression for ground motion versus distance on these noisy <br />measurements can produce highly uncertain results and there is no analysis of the <br />standard deviation of the fitting errors or confidence intervals for the regression. <br />Although the measurements were taken over the range from 10 to 200 ft from each <br />source, the regression results are extrapolated to a distance five times that of the <br />maximum measured distance, and ground velocities at these extrapolated locations are <br />reported to three significant figu s. This stated accuracy of the results is completely <br />unjustified. In reality, given the large uncertainty in the data, the limited range of offsets, <br />and the excessive extrapolation distance, extrapolated values for ground velocity at a 900 <br />ft. offset likely have an uncertainty greater than the attenuation rate being sought. In other <br />words, attenuation rate cannot be determined from this data, and formulas for the <br />regression lines are meaningless. Standard analysis of errors must be provided for any <br />experimental data in order to assess the validity of conclusions drawn from the analysis. <br />In addition to overstating the measurement accuracy, the author claims the values can be <br />used to predict what would be observed at the proposed quarry site. This conclusion is <br />simply not justified considering both the large uncertainty in the measurements results <br />and the dissimilarity of the two sites. <br />3) No description of field procedures, instrumentation, calibration procedures, or <br />sensor spectral response are provided. <br />A dozer and a backhce shovel used to rip bedrock will produce seismic energy <br />with a broad energy spectrum from less than one Hz to hundreds of Hz, but the spectrum <br />will be rich in low frequencies. High frequencies attenuate rapidly with distance from the <br />source due to a constant energy loss per cycle that results from frictional dissipation <br />(.Grant and West 1965). Low frequencies therefore transmit the most energy at lazge <br />distances, and it is important to have a sensor with very low resonance frequency as well <br />as a recording system with no low-cut filter in order to measure this important portion of <br />the energy spectrum. According to the Revey report the lowest frequency measured by <br />