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.: <br />hir. Dale I'.eam <br />Cooley Gravel Company <br />20 March 1975 <br />Page ? <br />bulletin, the only event which vas perceptible vras the blast <br />of 6/1?/72, since the L'S~.'.i sets the perceptibility level, by <br />empirical studies, at 0.04 in/sec.. <br />It is of paramount importance that the development of <br />natural resources proceed vrhile responding to le,~,itimate <br />concerns of surrounding individuals. As a result of t:iese <br />concerns the "Colorado School of I+iines Ad Hoc Coi.uaittee on <br />Ground I,:otion due to Blasting" made recoramandations cn <br />ground motion safety limits. These recommendations are <br />modifications of Pennsylvania State Laws, The :.d Hoc <br />Com.•aittee particularly suggested a change :in section 3 of <br />the Commor.::ealth of Pen.^_sylvania l+ct i;o, j62, July 10, 1957 <br />P.L. 685, as a-nended Juiy 12, 1961 and January 26, 1966, <br />as follovrs~ <br />"In blasting operations except as hereinafter cthervrise <br />provided, the maximum peak particle velocity of any one <br />of three (3) mutually perpendicualar components of the <br />ground motion in the vertical and horizontal directions <br />shall not exceed 2 inches per second at the immediate <br />location of any public building, school, church, <br />commercial or institutional building neither ovmed nor <br />leased by the person conducting the blasting, and shall <br />not exceed 0.$ inches per second at the inr,edia~l:e <br />location of any occupied dvrellinQ house neither ovmed <br />nor leased by the person conducting the blasting." <br />The Pennsylvania law originally set tyro inches per second a~ <br />the maximum velocity at all sites. The Ad Hoc Committee <br />considered a peak particle velocity of O.S inches per second <br />as an appropriate level for residential areas because it <br />"is under the 'intolerable' limit of 0.58 inches per second <br />as outlined in JSB^I Bulletin656." I~l- can be seen from the <br />particle velocity figures previously presented, that blasting <br />by the Cooley Gravel Company at Iforrison Quarry is well <br />below the limits set as a preceedent by Pennsylvania :Mate <br />la:v. Trris blasting is also within the more stringent <br />guidelines recommended by the A.d Hoc Committee on Ground <br />Liotion. Therefore, as long as Cooley Gravel does not exceed <br />a blast of 10,450 lbs, vrith a half dozen or more delays, <br />they will be in no danger of exceeding the Ad Hoc Committee <br />recomendations. <br />There is a total of ten seismographs, at eight different <br />