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<br />~~ ~%~~•~ M(CROGEOI'HYSCCS
<br />r/-^J~ COR!'ORATION
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<br />•; "July 24, 1979
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<br />"" " "~`~ ~ Mr. Gordon Hayes
<br />:; •; :: ,r WINSLOW CONSTRUCTION CGNiPANY
<br />,.; .~ 30002 South Huron Street
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<br />:--~' '~ Denver, CO
<br />"~ '+ Dear h?r. Hayes:
<br />+' i`",.~ Per our letter agreement of June 9, 1979 and sub_agc~nt com-
<br />~~' '=~ munication, MicroGeophysics Corporation has complat~:: a pro-
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<br />~~,„ •, a, gram of monitoring ground vibration induced by th= July 3, 1979
<br />~ production shot at Plinslow Construction Company's Dear Creek
<br />k Canyon Quarry and a review of seismic records frcm long term
<br />' ~.;~^.•- J,'seismic monitoring projects. This seismolcgical iav_stigation
<br />- '- 1 was undertaken to deterrnir.e the ground motion induce9 by quarry
<br />~:'~~ shots in the vicinity of the Painter house and adjacant slopes.
<br />~r~.. Tile program is responsive to requests of Mr. Ed Ande~sor. of the
<br />~ ';,~..+i.:;~:•--',~-~. Jefferson County Zoning Department. This letter describes the
<br />• ~-;;;~'~~:;,~ results of this study. This report is based on the field work
<br />~,,;.,~~'''~ and analysis by Dr. David Butler, Idr. Dean Brooks, Mr. Don
<br />'' ~~-'. ~ b~~.-,~ Hansen and Mr. Roger Bowman.
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<br />f ~~ '"~ Instrumental observations at four monitoring sites stow that
<br />~-~ -~ ground motion did not exceed 0.5 in/sec outside the ;carry
<br />_~`~';~.~' following the July 3, 1979 quarry shot. Evidence from remote
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<br />•" seismographs indicates that ground motion has not exceeded
<br />-a:._ '•'r 0.5 in/sec a~ the Painter 'rouse or rock overhang upsiope from
<br />O ~~~''"~' ~ the house in the past year. A maximum peak particle velocity
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<br />~.,.;- ~: of 0.5 in/sec is considered to be a conservative not-to-exceed
<br />(~ ~.'-':,,'' guideline in the explosives industry.
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<br />Results of the monitoring and seismic record review programs
<br />are summarized below:
<br />Mar:imum Peak Maximum Peak
<br />Particle Velocity Particle Velocity
<br />Measured for the Interpreted
<br />Site July 3, 1919 shot For Past Year
<br />Painter House
<br />Rock Overhang
<br />Ridge
<br />Conveyor (in
<br />the quarry)
<br />0.08 in/sec
<br />0.24
<br />0.44
<br />0.82
<br />0.12 i;./sec
<br />0.37
<br />0.67
<br />70900 'NEST aaTH AVE'JUE
<br />1.24
<br />WHEAT RIDGE, COLGRADO 80033 / (303) a2a-099
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