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Illllllllllllllllll ~ III IIIIIIIIIIIIIIII <br />STATE ~ COLORADO <br />DIVISION OF MINERALS AND GEOLOGY <br />Ueperllnnnl Ut Ndlur,t Itcwurre5 <br />I f l f Shcrmen 51., Room ! 15 Jllt~~~ <br />I~rnvrr, Colnrarln NO!O1 I I <br />Phonr: 11011 Hhb- 5567 <br />DEPARTMENT OF <br />NATURAL <br />December 12, 1997 ~SQ[J~CES <br />Roy Romrr <br />Gu.rrnrv <br />' IanwsS lwfihead <br />Mr. Ray Patterson F.rtwnr uut2mr <br />Holnam, Inc. <br />Mq heel a. ton[', <br />3500 State Highway 120 0,~~.~~„ Dneclrn <br />Florence, CO 81226 <br />RE: Norman and Lisa Bowie Blasting Complaint -Review of Data -Portland Limestone Quarry -File No. <br />M-77-344 <br />Dear Mr. Patterson: <br />Thank you for providing the Division with your data on the blasts the Bowies recorded and are concerned may have <br />damaged their home and the two blasts for which you monitored ground motion and air blast at their residence. Our review <br />of the data and the distance to the Bowie home revealed that it is improbable that your blasting operations for the dates and <br />times provided by the Bowies caused damage to their home. Ground motion and air blast from your operations appear to be <br />in compliance with Rule 6.5(4) of the regulations. The Division will not pursue this matter further, unless we get more <br />complaints of a similar nature. <br />It is your responsibility to cenduc[ operations in such a manner that off site damage wi(I not occur. We recommend that you <br />continue to monitor, for a while, blast vibrations (ground motion and air blazt) at the Bowie residence so that you will know <br />that your blasting is being conducted in such a manner az to prevent damage to their home. We also recotmnend that you <br />have the data from these blasts placed in the Division permie file. <br />Peak particle velocities at the Bowie residence are well below the threshold levels at which the Federal Office of Surface <br />Mining believes there is a minimal probability of superficial damage to residential type structures. Air blasts, however, <br />From your blazting operations occasionally are within the annoyance range to people living in [he vicinity. The annoyance <br />range is considered to be from 120 decibels up to the threshold limits of 129-133 decibels. On October 3, 7 and 16. you <br />measured air blasts at 113.1, 117.2 and 128.5 decibels respectively, at your north gate monitoring station. The U.S. Bureau <br />of Mines recommends keeping air blast levels to 110 decibels in order to reduce annoyance and complaints as much as <br />possible. It would, therefore, be advisable for you to keep air blasts below this level. <br />Il is very likely that more new homes will be built in the vicinity of the Bowie home. Holnam, Inc. should consider making <br />any possible changes to its blazting operations that will lessen the impact of blasting on the community. <br />Please call if you have any questions. <br />Sincerely. <br />Larry D. Ochler <br />Environmental Protection Specialist <br />cc: Norman and Lisa Bowie <br />Jim C. Stevens, DMG <br />Jlm Dillie, DMG <br />AI.tOtiSWMMITEMP7713iREV IDO <br />