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Scope of Work:
· First emergency project consisted of installing a debris barrier across the Schoharie Reservoir.
· With only twelve days allocated to complete the work, DAC forces took only six days to install the 2,000 linear foot boom, two shoreline anchors and three in-water mooring anchors.
· The second consecutive emergency contract commenced on January 6th, 2006, which was to install (4) siphons in order to lower the water elevation of the Schoharie Reservoir.
· 12-15 personnel worked double shifts removing the stone masonry facing and drilling five foot long, 1” diameter anchors into the cyclopean concrete on the dam in order to install six support frames at each siphon location.
· W-section beams with welded cross frames were erected onto 18” x 18” base plates in order to begin setting pipe sections and saddles in place.
· The siphon lengths range from 190 to 200 feet long. A 48” diameter steel draft tube rises thirty feet up from within the reservoir to where it elbows over the dam crest for another thirty feet to a 48” x 30” reducer. The pipe continues downstream one hundred feet toward the spillway at a fifty-five degree angle. At the base of the dam the 30” pipe meets a concrete anchor restraint and continues for another 30 feet to a 36” diameter outlet tee cast in a thrust block.
· Each siphon was shipped in seven separate sections that were welded together in the field.
· The four major heavy lifts consisting of the 48-inch draft tube and top horizontal took place with the help of a 200-ton Liebherr hydraulic truck crane.
· The majority of the remaining picks and frame erection was performed by a 100-ton Manitowoc lattice boom crawler rig.
· Erection, fit up, and welding of the support frames, saddles and pipe was completed in three weeks.
· With the reservoir water level dropping rapidly (about 12” per day), on March 1st two of the four siphons were tested successfully with a vacuum priming system. The remaining two were started once the water rose to an adequate level.
· DAC continued to provide siphon operation and maintenance while the remaining emergency measures were carried out on the dam, and extended their repair and operation services through November of 2008.
· The siphons were completed on time, in just two months, even with heavy rains causing the reservoir to rise above the dam crest delaying work for almost three weeks.
· The 20th Annual AGC/DOT Conference in 2006 featured this project.
· The siphons were part of the featured story in New York Construction Magazine in February 2007 and the emergency contracts were the Public Works Project of the Year.
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