_PERMIT FILE - M1981302 (25) - Laserfiche WebLink

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Total suspended particulate (TSP) concentrations were monitored by Flatiron Sand and Gravel on the Deepe Farm property during calendar year 1980 . From 53 24-hour measurements during the year, the annual geometric mean concentration was 40. 7 ug/m3 (micrograms per cubic meter) . The Federal Primary Standard for annual TSP concentration is 75 ug/m3. The Federal Secondary Standard is 60 ng/m3. Thus, current average TSP concentration on the property is well below the most stringent standard. The Secondary 24-hour Standard (which can be exceeded no more than once per year) is 150 ug/m3. The second-highest 1980 monitored 24-hour concentration at the Deepe Farm • site was 130 ug/m3, also below the most limiting standard. Other 24-hour values ranged from a low of 6 ug/m3 to a single high reading of 202 ug/m3. The State of Colorado, in its Air Pollution Implementation Plan for the Denver Metro region, estimates that the annual average background TSP concentration is approximately 30 ug/m3. Background refers to a "natural" pollution level in the absence of local man-made pollution sources . It should be realized, however, that background particulate • concentrations normally vary widely due to seasonal differ- ences in dryness and wind velocity. The 1980 data suggest �• G-4