Project Tag: cofferdam

Pit 5 Instream Flow Release Modifications

Global Diving & Salvage,Inc. was contracted to install nine 18” x 44” outlet gates on the upstream face of four existing wheel gates. The design required that the new gates be installed in a water depth of 20’. To accomplish the work Global provided engineering and cofferdam design of two 25 foot tall cofferdams which had a radius of 4’. The cofferdams were fabricated in the bay area and shipped to site where they were utilized.

To accomplish the work Global certified underwater welders installed pad eyes on the upstream face to attach turnbuckles. Willliams undercut anchors were also installed to provide hold down capabilities. After installing the cofferdams and working under confined space and fall protection regulations Global’s surface welders cut openings and installed bow outlet pipes,gates,and operator platforms on the upstream face. The work progressed and the cofferdams were moved from site to site. All work was tested and installed to clients high expectations. The work was completed on time and within budget.

Pit 4 Cofferdam Installation

Global Diving & Salvage,Inc. provided a dive crew to install and seal a 25’ x 15’ wide cofferdam to the face of Pit 4 Dam. The installation required the removal of 5.5 cubic yards of concrete. To accomplish the removal the divers utilized rivet busters,sinker drills and rock splitters. After removal of the concrete the cofferdam was installed with almost 40 epoxy anchors which were pull tested prior to tightening. The cofferdam is being installed to allow for a new 8 foot diameter penetration and gate through the existing dam. A new intake structure will subsequently be installed.