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7/28/2014 State.co.us Executi�e Branch Mail - Blasting Records for Trapper Mine <br />This calculation re resents an average, and fails to recognize that there are fluctuations throughout the blast <br />- during some delay periods there are fewer than 6 holes firing and during others there are more than 6 <br />6) The "Lbs / Delay Period" ent 2310# appears to take the "avera in " approach one steD further in that it <br />assumes that the same weight of explosives was used in all of the holes. [(Total Explosives) /(Holes Shot)]' <br />(Holes/ Delay Period). <br />7) Fig. 3.4 -4 of the permit (2nd Attachment) depicts a Typical Delay Scheme. Using the blaster's layout sketch <br />for Dec. 7 and drill hole /explosive logs, I attempted to construct my own Delay Scheme for this shot. I <br />selected this one because all of the delays, except for the initial 25 ms, (if my interpretation is correct) are <br />100 ms. My sketch is the 3rd Attachment, and it appears that rather than there being a consistent 6 <br />holes /delay, there are actually 3 instances of 9 and 3 of 8 holes /delay. Because the depth of hole (and <br />therefore wt. of explosives) increases toward the bottom of the page, it appears that the maximum Lbs /Delay <br />Period is actuallti3900# rather than the 2310# reported on the Summary form. <br />8) The Scaled - Distance formula for the nearest building (4904') allows up to 7,950# per 8ms delay (see 4th <br />Attachment), which is still significantly higher than the 3900# 1 calculated, so in this instance, it does not <br />appear that the allowable weight was exceeded. However, if this averaging method of calculating the <br />Lbs /Delay laeriod is used consistently, it is conceivable that the threshold may be exceeded on occasion. <br />9) The sketches provided with TMI's Blast Summaries do not readily facilitate determination of the blasting <br />sequence and the number of holes that fire in a given delay period. As I said, 1 am not certain that my sketch <br />is an accurate representation of what occurred on Dec. 7. Sketches for the other three Shots I reviewed were <br />even more difficult to evaluate; the Delays used were not all the same length, and I was unable to derive even <br />a potential sequence. <br />1 request that Trapper Mining, Inc. review the information I've compiled and presented here, and respond at <br />the company's earliest convenience. <br />Best regards, <br />Marcia <br />Marcia L. Talvitie, P.E. <br />Environmental Protection Specialist II <br />Coal Regulatory Program <br />COLORADO <br />* Division of Reclamation, <br />Mining and Safety <br />Department of Natural Resources <br />P 970.247.1184 1 F 970.247,5104 1 C 970.903.7597 <br />DRMS - Durango Field Office <br />691 Co. Rd. 233, Suite A -2, Durango, CO 81301 <br />marcia.talvite @state.co.us I http: //mining,state.co.us <br />4 attachments <br />dn 2013 -12 -07 BiastSummary.pdf <br />1160K <br />hftps:l/mai I .g oog I e. comlmai 1 /u/01 ?ui= 2 &i Ir 91 a975f658 &vi evv=pt &search= sent &th= 1477e1 &4bfb858ca &si ml = 1477e1 e4bfb858ca 213 <br />