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Terry Tunnel Bulkhead <br /> Construction Certification Report <br /> Page 3 <br /> Quantification of perimeter area irregularity was accomplished <br /> by measuring x-sections within the bulkhead lenq_th and using <br /> the generated x-sections to quantify intrusive area verses <br /> total area between sections. <br /> This method provided an estimate of rock area irregularity of <br /> 69% which exceeds the design and committed minimums specified . <br /> Pre-pour approval by DMG was required (and received) that this <br /> design assumption was met. <br /> The bulkhead dimensions and rebar placement met or exceeded <br /> all design specifications and assumptions. These items were <br /> also inspected by John Abel , design engineer and DMG prior to <br /> the pour . <br /> Specifically these are: <br /> 1) a depth of 8 feet (distance between forms) <br /> 2) an air side rebar placement of #10 at 7" x 7" . <br /> 3) an air side rebar cover of 3 1/2" . <br /> 4) a water side rebar placement of #6 at 12" x 12" . <br /> 5) a water side rebar cover of 3 " . <br /> 6) a dimension of 11 feet for reinforced bending length ( ie <br /> rib to rib dimension) . <br /> 7 ) a rebar-rib clearance of less than 6". <br /> 8) a minimum rebar lap distance for spices or continuous <br /> bars. <br /> 9) a minimum perimeter area irregularity of 10% . <br /> 10) a clean wall , back and sill surface within the bulkhead <br /> with all loose rock removed . <br /> 11) the placement of the diversion and monitoring pipes. <br /> 4d) Pumping of concrete and filling of forms as well as seven and <br /> twenty-eight day compression tests for concrete strength. <br /> The same concrete mix and additives were used for the Terry <br /> Tunnel bulkhead as was successfully used for the previously <br /> poured bulkheads . <br /> Concrete pumping was started at approximately 3 : 30 pm on <br /> September 1, 1994 and filling of the form started shortly <br /> after 4 : 00 pm after a considerable delay spent working on the <br /> concrete pump. A piece of dirt had lodged in one of the <br /> hydraulic valves that operates the concrete cylinders. After <br /> initial startup, the pour proceeded smoothly and was completed <br /> by 11: 30 pm. <br />