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w,__.. , <br />;.~ <br />~~ <br />i:; : ,j ~ <br /> <br />~~ ~%~~•~ M(CROGEOI'HYSCCS <br />r/-^J~ COR!'ORATION <br />' l _. <br />._~` - <br />•; "July 24, 1979 <br />,,,~ <br />"" " "~`~ ~ Mr. Gordon Hayes <br />:; •; :: ,r WINSLOW CONSTRUCTION CGNiPANY <br />,.; .~ 30002 South Huron Street <br />.L <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- <br />~: .1,''. <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. <br />~ 4~ ,. <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 <br />:~., ..- <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 <br />~. ~j <br />~.,.;- ~: of 0.5 in/sec is considered to be a conservative not-to-exceed <br />(~ ~.'-':,,'' guideline in the explosives industry. <br />' i ~', <br /> <br />I:r,--~... <br />` ,,,~ <br />~., :o <br /> -y <br />' ,~ <br />y <br />,,....=~~ <br />~ <br />, <br />. <br />. <br />• ~,_ ~ <br />, , <br />~ <br />' ' <br />1 - <br />? <br />~ " -°- <br />I.' . <br /> <br /> <br />r , ~`~' <br />i - } . <br />~.~ -- •. <br />^. .: <br /> <br />+ ...~ <br />~ <br />~ <br />' <br /> ~ <br /> „, <br /> . <br /> ~ <br />..- . <br />,. <br />y <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 <br />