Leesville – Caisson 7 Floating in Forebay
FLOATING BULKHEAD PROJECTS
Leesville Floating Bulkhead , Leesville , Virginia
The Leesville Hydro Facility , operated by Appalachian Power , is part of the Smith Mountain pump storage system . At five-year intervals , the Federal Energy Regulatory Commission ( FERC ) requires that the spillway gates be fully opened to demonstrate their capability .
The Leesville Hydro Facility has four spillway gates that are 50 feet ( 15.2 meters ) wide and 35 feet ( 10.7 meters ) high . The spillway bays are not equipped with stoplog slots for the installation of stoplogs to dewater the gates for inspection , repair , or to demonstrate the capability to fully open a gate . A fully open gate can pass up to 38,900 cubic feet of water per second ( 1,101.5 cubic meters of water per second ). The flood stage at Altavista ( the first city downstream ) is 19,300 cfs . ( 546.5 cms ). Consequently , Appalachian Power needed a way to prevent water from flowing through the spillway while the gate was open .
In 1993 , Appalachian Power designed a temporary bulkhead system to dewater the spillway and allow for the opening of the gate . The temporary bulkhead system consisted of removable knee braces on the upstream entrance to the spillway and seven bulkhead sections that stacked on the knee braces and sealed against the pier noses of the spillway . The knee braces weighed 4,000 pounds ( 1,814.4 kilograms ) each . Three of the bulkhead sections weighed 48,000 pounds ( 21,772.4 kilograms ) each . The other four sections weighed 70,000 pounds ( 31,751.5 kilograms ) each . All these components required a barge-mounted crane , and the work had to be executed by a team of divers .
The bulkhead system was installed for the first time in 1994 . The opening demonstration was repeated in 1999 . It required seven weeks to set up , demonstrate gate capability , tear down , and store . The process was again repeated in 2004 and 2009 with a seven-week duration each time . The cost of installation increased with each iteration . Thus , the client expected the 2014 installation to take longer and cost more .
In the spring of 2015 , proposals were requested from eight companies ( including the successful bidders from 2009 and 4 | THE FLOATING BULKHEAD