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BLASTING EFFECTS 6 CONTROL INTRODUCTION: Vit~ra-Tech Engineers, Inc., have been retained by Arkins Park Stone, to inspect and report on the possible effects of blasting operations at several small flagstone quarries along N. County Rd. 27, in the vicinity of Arkins Park, Lorimer County, Colorado. Some of these quarries originated as Union Pacific Railroad quarries and have been worked since 1887. The present operators of Arkins Park Stone have been working existing and also unused quarries in the area for 33 years. A visit was made by Vibra-Tech Engineers, Inc., to inspect the existing quarry sites, and to discuss the blasting methods used in these quarry areas, on April 15, 1986. QUARRY OPERATIONS AND BLASTING: It is important to recognize that while the terms "quarry" and "quarry operations" and "quarry blasting" will be used throughout this report, the Arkins Park quarries are not typical of most quarry operations, since large naturally delaminated sandstone flags are the primary product, and "breakage" as in conventional blasting opera- tions is not sought after, nor are there any crushing operations in the quarries. The only Location in the vicinity where conventional drill and shoot blasting is carried o~}t_,'whe e t r ugh breakage of the shot rock is an objective, is at the ~ where this conventional blast- ing is only used to remove the unwanted overlying rock cover, or "over- burden". The product material at this quarry is no[ shot at all. The ~~hi~l~ sp Qu~~y_does not, however, belong to the Arkins Park Stone operation. Conventional quarry operations normally try to achieve a thorough and extensive "breakage" when they carry out blasting operations. The more completely [hat the explosive energy can be utilized to break rock up as finely as possible, the less mechanicai energy, and wear and tear, has to be utilized at the crushing operation in the quarry. The Arkins Park Stone quarries, however, are using very small amounts of explosives to dislodge large sections of sandstone, along existing natural cracks and laminations. Fine breakage is not sought after: the shots themselves are a Eew small holes, approximately 1§ inches in diameter, spaced widely apart - 6 to 8 feet or so - drilled along natural cracks and fissures. Maximum total explosives weight fired varies from 5 pounds to 30 pounds. Arkins Parlc Stone would like to be free to fire up 50 pounds of explosives, and this; maximum weight is allowed for in all predictive cal- culations in this report. All shots are fired simultaneously: holes are not delayed. Becau;;e of the small weights involved, and because predictive calculations are onlly concerned with explosive weight detonated in any one instant of time, in each "delay period", this report will use the conven- tional term "pounds per delay" [o avoid confusion. IC is to be understood therefore that in this report, discussing blasting at the Arkins Park Stone operations, when the term "pound per delay" of explosive is used, it refers to the weight: of explosives detonated at any one instant of time, and also to the Cote~l weight of explosives detonated on the entire shot. Therefore, for the purposes of this ceport, total or maximum charge weight and charge per delay are synonymous.