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American Tunnel Bulkhead No.3 Construction Certification Report Page 5 Low aressure troutin~ of the concrete-rock contact After construction of the air-side bulkhead form and placement of rebar, the form was marked for drillhole collars by nailing faucet washers to the form at the selected locations. One ring consisting of nine holes was drilled to intersect the rock contact along the perimeter at approximately the mid-point or center of the bulkhead, The target points were selected and then appropriate corresponding collar points were selected such that the hole could physically be drilled without hitting the rebar mat. Angles and distances were measured so the selected lines could be reproduced after the bulkhead form was stripped. The bulkhead was drilled and the contact was low pressure grouted the week of November 25, 2002. Each hole was pressured to 200+ psi with very little grout take although one series of holes appeazed to take grout into the formation. These holes were re-drilled on successive days and grouted until refusal, The construction pipe was permanently closed on December 3, 2002 and additional formation grouting was done downstream of the bulkhead for the remainder of the week. Very little grout was accepted during this process. Construction Drain Pine Closure The construction drain pipe was permanently grouted closed and capped on December 3, 2002. A grout pig was pumped ahead of the grout to separate the water and grout. The catch bars placed in the up-stream end of the pipe provided a stop for the grout pig allowing complete and total filling of the pipe. The valve was closed under pressure to prevent bleed-off. After curing of the grout in the pipe, the valve was removed and a stainless steel blind flange was bolted to the pipe flange. The pipe has been permanently sealed. The American Tunnel Bulkhead No.3 construction meets or exceeds all design specifications.