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this residual fine material with whatever native soils that can be salvaged before extraction, will assure a <br />sustainable growth of rangeland vegetation, even with relatively shallow soil depths. <br />2. Regardless of what most professional agronomists consider to be ideal soil depth conditions, the native <br />growth in the very shallow in-place soils (measured in single-digit inches) that cover the essentially <br />monolithic Dakota Sandstone effectively demonstrate the capacity of these less-than-ideal conditions for <br />supporting adequate vegetative cover. The conditions following the rock extraction shall be somewhat <br />similar to those native conditions, but with evenly distributed soils and the added advantage of a nearly <br />flat, level remaining surface. Soil erosion conditions are thereby considerably reduced, as well as much <br />lessened precipitation run-off, leaving the natural moisture for the benefit of the vegetation growth. The <br />applicant's acceptance of an estimated 2-foot depth of soil to be replaced for purposes of estimating the <br />bond amount for the initial warranted operations is not a commitment to furnish reclamation replacement <br />soils in depths of 2 feet. Only the available on-site plant growth media can be furnished. <br />3. The blasting contractor, Blasting & Mining Inc., of Cortez, CO has 30 years of extensive blasting <br />experience within the local azea and especially with the subject Dakota Sandstone at this site. They utilize <br />the Bureau of Reclamation blasting safety guidelines, are OSHA compliant, MSHA trained, and qualify as <br />a licensed, insured blaster. The site azea has been quarried with explosives (much of it by this very <br />blasting contractor) for 30 years with no reports of any damage from blasting. <br />Blast vibration data is available from published values of the explosives manufacturer, Dyno Nobel. <br />Calculations using Dyno Nobel data show that it is relative simple to limit the shock vibration <br />(acceleration) to a structurally safe 1/2 -inch per second squared out to a 5,000-foot radius within a <br />continuous hazd-rock bed. <br />The initial blasting plan for the project proposes 3'/s-inch drilled hole diameter for an 8-foot to 5-foot <br />center-to-center pattern in up to 24foot hole depths. Using a 9milli-second delay and an ammonium <br />nitrate explosive charge and 2x8 Hercules Dynamite primers with non-electric (gas) caps, a powder factor <br />of 0.65#/CY will fracture a burden of 56.89 CY per hole per delay (8-foot pattern) with 37 pounds of <br />explosive. <br />Fora 3'/z-inch diameter drill-hole, ammonium nitrate explosive, at 3.75#/foot, will fill about 10 feet of the <br />24-foot deep hole, leaving 14 feet of stemming at the top of the hole to control fly-rock and sonic shock <br />with a virtually undamaging ... <br />a) less than''/x-inch per second per second acceleration, <br />b) frequencies of around 200 cycles per second, and <br />c) no measurable peak particle velocity. <br />[Note: Structural damage begins occurring at accelerations of 2 inches/sec/sec and above, in the <br />neighborhood of 10 cycles/sec and less, and with discernable peak particle velocity. ] <br />Colorado law [CFR 30, Sections 715.19(e)(2)(ii)(c)(1), 816.57(d(3)p), and 817.57(d)(3)(~) ]requites no monitoring for <br />a scaled distance (Ds) of 55 or more, where scaled distance equals the actual distance (>300 feet} from <br />the blast in feet (D) divided by the square root of the weight in pounds of the explosive (W) when feed <br />with delays of more than Smilli-seconds . <br />[Ds=D-~IW] <br />File: C/MesaSS /AdegResp <br />