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Environment,inc,. ' Page 4 <br />"Albert Frei,ar~d Sons,,inc ~. ~ ~- ~ - : <br />" ~ .Walstrum.Aygregate Quarry ~ ~ ~ , . . <br />' M.L:R.B. Permit M-83-033 " <br />change in the amendment, but the maps show the Commercial <br />Designation. No grading or seeding will need to be ,done to <br />complete,reclamation in the commercial areas. <br />6:, Discussions are still taking place on moving the powerline. No <br />,.mining will"take place on the.new area within 200 feet of the line <br />until this issue is resolved. <br />7. Ala0.'s review, as addressed below. . <br />' - July 2 Letter <br />This'response it to Alan-Sorenson's review of the Geotechnical <br />-report,by Revey and Associates. Alan. suggests incorporating three of <br />the report'-s recommendations as enforceable components of the <br />Reclamation Plan. 'Frei has begun to incorporate"the recommendation ins <br />the'REVEY report as mining progresses. Many of-them will take some <br />.time to fully implement because of the amount of material that needs to' <br />be moved, in particular the:heights and depth of benches. Others like <br />number l-below have 'been incorporated into the mining methods used at <br />this time, Albert. Frei and Sons, Inc., will commit to using those <br />recommendations duri-ng mining and reclamation. <br />1. Mining-that will create north facing quarry walls striking <br />from N95°W to N45°E is prohibited UNLESS the excavation is <br />accomplished by gradually extending benches orthogonal to <br />thenorthfacing wall using progressively shortened <br />blastholes to create a final slope with.an angle matching <br />the dip of the formation. <br />2: -Air-Decked charges, as described in the REVEY report, will <br />be used for blasting at-all final quarry perimeter walls. <br />3. All blasting withiri 192 feet of the .final quarry walls will <br />conform to the following millisecond timing. These are made <br />part;of our blasting plan also.. <br />4. Diameter of the explosive charges will be limited to 6.5 <br />inches or less. <br />Alans' -note regarding: Mr. Revey's recommendation t'o mine from the <br />-top-down is .consistent with how the quarry is operated at this time. <br />The difference is that in the past, once a bench was started it was <br />'. worked•from top down leaving large vertical .displacements and wide <br />benches which .differs from Mr. Revey''s recommendations. Now two to <br />' three benches are worked from top to bottom. This increase the bond, <br />but does not decrease. the stability of the mine face. <br />After reviewing Mr. Sorenson's explanation of how the division would <br />calculate the-bond I concur with it in theory. I feel we can adapt it <br />to figu;e the .amount of-material needed to be removed to create the <br />mine face,as.described in the approved. Reclamation Plan. <br />INTER-ROW DELAY RANGE <br />(PER UNIT OF BURDEN) HOLE TO HOLE DELAY <br />RANGE <br />3'to l0 ms/ft 8 to 17 ms <br />