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Memo to Kate Pickford 2 December 19, 2007 <br />Blasting Vibration Control Plan File No M-2007-080 <br />DISTANCE - FT. MINIMUM Ds MAX. CHARGE WT./DELAY, LBS. <br />1,000 55 330.6 <br />2,000 55 1,322.3 <br />4,224 aberkon House 55 5,898.2 <br />5,000 55 8,264.5 <br />5,100 65 6,156.2 <br />2. Reference to the table above shows that the Scaled Distance Equation is rather restrictive for <br />blasting in close proximity to potentially affected structures. The nearby (within 200 feet) <br />structures to the proposed blasting are barb wire fencing, irrigation pond and pump, Las Mesitas <br />Ditch, and a farm service road. There is an irrigation pivot 750 feet form the blasting location, and, <br />as mentioned above, there is a house owned by Mr. William Haberkon located 0.8 miles from the <br />blasting. The Scaled Distance Equation is designed to limit blasting vibrations to a point where <br />preexisting cracks in plaster walls will not extend or separate as a result of the vibration level <br />imposed. Therefore, the types of structures that are closer to the blasting than the Haberkon House <br />are not the types of structures that are very sensitive to blasting vibration, and the Haberkon House <br />is the logical control structure for proposed blasting operations. Reference to the table in item no. 1 <br />above shows that 5,898 pounds of explosive could be shot in the proposed pit and be protective of <br />the Haberkon House. This amount of explosive is orders of magnitude greater than that proposed in <br />the permit application. <br />3. The Merritt Report suggests that pre-blast surveys of all nearby structures out to the Haberkon <br />House be conducted. The DRMS will make it a permit requirement to conduct pre-blast surveys of <br />the fences, farm road, pond and irrigation pump, and sprinkler. The pre-blast survey must be <br />conducted prior to initiation of blasting in the pit, and the pre-blast survey reports must be provided <br />to the DRMS for inclusion into the permit file. The DRMS endorses the Merritt Report suggestion <br />to conduct a pre-blast survey of the Haberkon House, but will not make such a survey a requirement <br />of the permit since the house is outside that one half mile radius in which pre-blast surveys are <br />typically required. <br />4. The DRMS requires all Operators using explosives to complete a blasting report for each shot. The <br />report must be retained by the Operator for at least 3 years and be available for inspection by the DRMS <br />on demand. The record shall contain the following data: <br />a. Location, date, and time of blast; <br />b. Name, signature, and license number of blaster-in-charge; <br />c. Identification, direction and distance, in feet, from the nearest blast hole to the nearest <br />potentially affected structure, such as any dwelling, school, church, or community or <br />institutional building either: <br />i. not located in the permit area; or <br />ii. Not owned nor leased by the person who conducts the mining operations. <br />d. Weather conditions, including temperature, wind direction, and approximate velocity; <br />e. Type of material blasted; <br />f. Sketches of the blast pattern including number of holes, burden, spacing, and delay pattern. <br />Sketches shall also show decking, if holes are decked to achieve different delay times within a <br />hole;