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Memo to Tom Schreiner 7 February 21, 2006 <br />Bulkhead Cost Estimate Permit No. M-1983-141 <br />(A, - 75.982)(58830A, - 74998.82) = 0 <br />A, _ 74998.82 -1.27 square inches per foot of beam is the reinforcing steel area required <br />58830 <br />Standard #9 rebaz has 1.00 squaze inch cross section, so installation of #9 bars on 9 inch centers, both ways, <br />yields: <br />AS _ 1.Osq.in. =1.33 squaze inches per foot of beam reinforcing steel area <br />0.75 ft. <br />where: C =compressive bending force (lb) <br />~ = ACI strength reduction factor; 0.85 shear concrete; 0.90 flexure rebar <br />f'~ =concrete compressive strength (psi) <br />b„, =beam web width = 12 inches <br />a =compression zone depth (inches) <br />T=tensile bending force (pounds) <br />AS =area of rebaz (square inches per foot) <br />fy = rebaz yield strength = 60,000 psi for standazd bars <br />M„ =maximum bending moment (foot pounds) <br />W =pressure (dead) load (pounds per foot) <br />P = adit width (feet) <br />M„ =design bending moment (foot pounds) <br />d =distance, extreme compression fiber to rebaz centroid (inches) <br />L =bulkhead length (feet) <br />m~ =minimum cover, form face to rebar surface = 3.5 inches <br />Design of the Main Bulkhead for Construction Cost Estimating Purooses <br />The basic design elements for the proposed main bulkhead aze as follows: <br />• bulkhead dimensions are 8' x 8' x 6.5' long <br />• bulkhead volume is 15.4 cubic yazds <br />• low pressure grouting is necessary <br />• flexural reinforcing at the bulkhead outby end is #9 bazs on 9 inch centers, both ways <br />• temperature shrinkage rebaz at the bulkhead inby end is #6 bazs on 12 inch centers, both ways <br />• stainless steel bypass and monitoring piping is necessary <br />• Concrete will use maximum'/n inch aggregate, Type V cement, 16 percent fly ash, pozzolan, <br />water/cement ratio of 0.45 by weight, and will be over sanded to enhance pumpability <br />The hydrostatic head that may develop at the secondary bulkhead, assuming little or no communication of <br />pressure from the mine pool impounded by the main bulkhead to the secondary bulkhead, is the difference <br />