FISHBURNE TUNNEL

With construction starting in 2011 and a budget of nearly $200 million, some have called the Spring-Fishburne the largest and most complex infrastructure project in the history of Charleston, SC. However, as this critical drainage project is nearing completion, the city says neighbors on the peninsula could see significant changes as soon as that happens.

Throughout all its construction phases, Argos has delivered close to 10,000 CY of concrete, supplying Conti Civil Construction with the means needed to finish tunnel station 5. The primary Pump Station Structure and the Outfall have been built with reinforced concrete (4ft thick concrete base slab, 4ft and 3ft thick concrete walls, and a roof with a thickness that varies from 1ft to 2’-8”).

One of the significant elements of this phase was the installation of a temporary cofferdam to excavate and start building the permanent structure, a pump station 35ft below ground level that will tie to the existing drop shaft with a depth of 175’ where the main tunnel was already built. The job’s most critical technical component was installing three 66-inch 4,000-pound sleeves (stainless steel pipes). These sleeves connect to the main dewatering pumps. For everything to line up perfectly, the sleeves must be installed within 1/100th of an inch (think a couple of hairs thick) within the specified elevation.

Once completed, this major infrastructure project will provide the city with drainage improvements that will help ensure less frequent and less extensive flooding.