PODED-G- General Guideline for Drilling and Blasting Coral Reef for Armor Stone at Enewetok Atoll, M.1. a. Drill 24-inch diameter holes in reef crust layers less than six feet thick beginning with a 5'x5' array in a rectangular pattern. Drill 3 and 4 inch diameter holes where the reef crust is more than six feet thick. The hole array will exceed 5'x5'. b. Use 40 or 50 percent weight strength, water resistant, The powderstraight pelatin dynamite with instant caps and prima cord. rock ratio should bebetween 1.0 and 1.6 pounds per cubic yard depending on hardness of rock. rock, c. A smaller charge is used in harder (slower drilling) Experience and trial and error under controlled conditions will furnish additional guides as work progresses. 4. The amount of blasting energy used per hole should be no more then necessary to crack the reef crust. I£ heaving and distortion occurs the powder-rock ratio should be reduced or the shot hole spacing increased or combination of both. 5. The best recovery (percentage yield) of armor stones will be obtained by excavating the pieces from the cracked reef crust. 6. A quarry should be developed to provide two or more faces which helps to relieve blasting stresses and makes excavation of large pieces easier. A sigzag (angled) quarry layout would provide the greater number of working faces. 7. Joints, cracks and surge channels in the reef crust should be 8. Solution sinks, pot holes and cavaties will absorb blasting energy considered free faces when planning shot holes. and should be avoided in planning shot holes, 9. Blasting formulas referenced in paragraph 1, hereinbefore, lists the many additional items and variables effecting blasting techniques. The culmination of experience in the field will ultimately dictate the most successful blasting procedure.