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TR-14, File No. M-77-378 <br /> Page 3 <br /> c) The flow from the Terry Tunnel will be monitored for <br /> tracer if the valve is left open after tracer has been <br /> introduced into the Sunnyside Mine. A concentration <br /> balance will be established downstream so that any tracer <br /> concentration detected by the downstream monitoring <br /> program can be differentiated from any tracer that may <br /> have exited the Terry Tunnel. This information will <br /> become a part of the annual report. <br /> d) The pipe will be grouted full when it is determined that <br /> it will no longer be needed . <br /> 3) The American Tunnel bypass pipe design as approved consists of <br /> a 12 inch diameter, Schedule 80 steel pipe with shear studs <br /> placed at intervals along the pipe. While the design called <br /> for Schedule 40 steel pipe as adequate, the commitment was <br /> made to install the heavier wall Schedule 80 for increased <br /> durability. <br /> SGC is submitting the following alternate designs for approval <br /> with the option for SGC to select between the approved design <br /> or alternate designs based on construction ease, economics and <br /> estimated time of before valve closure at the time of <br /> construction. These alternate designs are listed below and a <br /> design analysis by John Abel is enclosed. <br /> a) Replace the shear studs on the Schedule 80 steel pipe <br /> with a thrust ring of adequate shear capacity. The ring <br /> would be 1/2 inch thick and have an outside diameter 6 <br /> inches larger than the pipe. It would be placed at least <br /> 6 . 5 feet from the downstream bulkhead face to distribute <br /> thrust and shear forces. This alternate design provides <br /> more metal to resist thrust in shear than the proposed <br /> shear stud usage and allows for fabrication under shop <br /> conditions verses field conditions. <br /> b) Replace the Schedule 80 steel pipe with a combination of <br /> stainless steel and HDPE. The stainless steel pipe would <br /> extend from the valve into the bulkhead. It would be a <br /> 12 inch diameter , Grade 316L, Schedule 40 pipe with a <br /> Grade 316L stainless steel thrust collar . The thrust <br /> collar would be 1/2 inch thick and 18 . 75 inch outside <br /> diameter welded to the pipe on both sides. The thrust <br /> collar would be located 6 . 5 feet or more from the <br /> downstream face to distribute thrust and shear forces. <br /> The remainder of the pipe within the bulkhead would be <br /> nominal 12 inch HDPE with two seep rings. This pipe will <br /> be fully supported by the concrete within the bulkhead <br /> and have equalizing pressures (outside and inside) where <br /> it extends upstream of the bulkhead. <br />