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• Construction and the approved detail drawing. All welding shall be in accordance with <br />AWS Dl.l structural welding code including operator and procedure certifications. <br />Formwork shall contain all inserts, pipes, anchors and cut-outs for grouting and pumping <br />concrete. <br />3.4 Installation <br />3.4.1 Grout Pipes and Water Pipe <br />The Contractor shall furnish, fabricate and install all grout pipes in the cast-in-place plug <br />as approved by the Engineer. One end of the grout pipe shall be attached to the rock wall using <br />masonry anchors and the other threaded end hall be securely fastened to the formwork. <br />Other air relief pipes, as necessary shall be attached to the rock in the same manner while <br />the other end extends through the forms, Grout and air relief pipes shall be temporarily <br />capped or plugged to prevent entry of foreign matter until ready for grouting. <br />In addition, the Contractor shall furnish, fabricate and install the water pipe through the <br />cast-in-place concrete plug to conduct the water being produced upstream through the <br />construction area. This pipe shall be as shown on the Drawings, complete with seal <br />rings, inlet decant risers, etc. <br />• 3.4.2 Formwork <br />The Contractor shall install formwork at the locations shown on the drawings. Forms are <br />to be mortar tight. The Contractor shall construct the formwork to suit the contour of the <br />excavation or the surrounding adit tunnel support. Any existing adit tunnel support shall <br />not be significantly modified to suit the forms, however, rock may be trimmed or chipped <br />to suit where interferences are encountered. The installation of the formwork shall be <br />reviewed and approved by the Engineer prior to proceeding with concrete or cellular concrete <br />placement. <br />The forms on the upstream side of the cast-in place concrete plug remain permanently in <br />place while the formwork on the downstream side shall be oiled or receive an application <br />of release agent. <br />Temporary openings/holes in the forms shall be provided where required to facilitate <br />access for cleaning of the rock surfaces inside the forms and for inspection and installing <br />grout pipes and concrete placement pipes. Small holes shall be made in the top of the <br />accessible side of the forms to allow visual observation of the progress of the concrete <br />placement. These holes will be plugged as the concrete or cellular concrete level reaches <br />them. <br />Form ties that extend completely through the plug from one side to the other shall not be <br />• used. <br />