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pounds of explosives. This amount of explosive results in a ratio of approximately 1 to <br />1.11 tons of material produced per pound of explosive used. This indicates a rather <br />heavy load ratio. On site testing may determine that they can use a lighter load than <br />initially anticipated. <br />The DuPont Blasters' Handbook, fifteenth edition, indicates that in order to keep <br />the velocity of vibrations caused by blasting within acceptable levels for structures <br />located 200 feet from the blast, 92 pounds of explosive maximum should be used per <br />each delay in a multiple delay shot. For structures within 300 feet, 116 pounds of <br />explosives is the maximum per delay. At the nearest point of 250 feet to structures in this <br />operation, the extrapolated maximum amount of explosives per delay is 104 pounds. A <br />portion of the DuPont table is produced below to use as a guide for determining numbers <br />of delays per shot: <br />Distance for blast area to nearest <br />structure, neither quarry owned nor <br />leased, in feet. <br />Maximum quantity of explosives per <br />shot for instantaneous firing or per <br />delay, for delay firing in pounds. <br />100 <br />200 <br />300 <br />400 <br />500 <br />600 <br />700 <br />800 <br />900 <br />1000 <br />1200 <br />75 <br />92 <br />116 <br />140 <br />176 <br />209 <br />259 <br />330 <br />403 <br />495 <br />770 <br />The nine- to ten-hole shot pattern, fully loaded, would result in using at least 2 <br />delays for the shot at the nearest location to the structures. When the face reaches its <br />farthest distance to the structures of approximately 700 feet, 259 pounds of explosives is <br />the listed maximum amount per delay. Shot sizes and the necessary number of delays <br />must keep the maximum amount of explosives per delay within the distant dependent <br />quantities listed in the table. Using millisecond delays will also reduce the effects of any <br />blasting seismic vibrations. <br />If the recommendations are followed, there should be no damage to the structures <br />mentioned above from the blasting operations. <br />In addition, I recommend that the operator have an inspection completed of each <br />of the structures mentioned including the residence 0.8 miles away prior to commencing <br />any blasting operations. Note any structural problems such as cracks, dents, un-level <br />structures, etc. Numerous pictures should be taken as part of this report with the proper <br />date and time of the pictures noted. The reports and pictures could be invaluable should a <br />claim arise in the future regarding damages due to blasting.