LITTLE HICKMAN — The 113-year-old dam on the Kentucky River that holds the water supplies for Nicholasville and Lancaster is being replaced.
Work began in June on the new Dam No. 8 near Camp Nelson between Jessamine and Garrard counties. The project, which will cost more than $12.6 million, should be finished by June 2015, said Jerry Graves, executive director of the Kentucky River Authority, the state agency that maintains the locks and dams.
"They're moving right along," Graves said of the contractor, Aquarius Marine. "They're ahead of schedule right now, and I'm very pleased."
Part of the existing dam was constructed of timbers that were filled with rock and then capped with concrete. It is the last "timber crib" dam on the Kentucky.
The lock and dam nine miles south of Nicholasville was built for about $300,000 from 1898 to 1900 by a contractor for the Army Corps of Engineers. The lock was able to lift a boat 18 feet, which was the highest lift of any lock and dam in the United States built prior to 1900, according to Kentucky River Development: The Commonwealth's Waterway.
John M.G. Watt, the engineer who designed Lock and Dam No. 8, later surpassed that by designing a lock on the Tennessee River with a 39-foot-lift in 1909; he followed that in 1912 with a lock on the Panama Canal with an even higher lift.
A significant amount of water leaks through the dam's foundation because of the underlying karst geology, which consists of fissures and fractures in the limestone rock. One estimate put the leakage at 12.7 million gallons a day, which is four times what the city of Nicholasville draws each day from the river.
"That dam has historically always leaked," Graves said. "They've had some problems with that since the day they built it."
Until about three years ago, the leaks didn't affect the water supply for Nicholasville and Lancaster because Lock and Dam No. 9 at Valley View also leaked into the pool held by Dam No. 8, said Tom Calkins, public utilities director for Nicholasville. But when a new Dam No. 9 was finished in 2010, that meant the 17.5-mile pool behind No. 8 could drop significantly.
"So now I don't have any leaks coming into the pool, and now it drops really fast in the pool 8 elevation because I still have the old leaky 8," Calkins said. "Things are going to be in the best shape they've been in decades and decades when we get this new dam 8 put in because we'll have those leaks stopped."
In addition, maintaining more water behind the dam will mean fewer algae blooms and improved water quality, Calkins said.
"It makes the treatment process easier and less expensive," he said.
The new dam will be a row of three steel cylinders, each 56 feet in diameter and filled with concrete. Aquarius Marine, the contractor, is a subsidiary of C.J. Mahan Construction, which completed the new Lock and Dam No. 9 at Valley View. That dam holds a pool from which Lexington draws some of its water.
In the coming days, the first continuous pouring of concrete will be done. For 24 to 36 hours, concrete will be poured nonstop into the first "cell" or cylinder. A temporary cement plant was built next to the dam. The cement plant will be removed when work on the dam is finished.
Renovation work also will be done on Lock No. 8 next to the dam. There has been some discussion about reopening the lock to recreational boat traffic as a way to promote tourism in the area, said John V. Carpenter, a former state legislator for Jessamine County who is now emergency management director there.
"It was never proposed to stay open year-round," Carpenter said. "It was either a weekend-type thing or a couple of months during the peak times of the summer for recreation. Also, there was talk of moving equipment between (Locks) 7, 8 and 9 if they had to do any work or repairs."
Jessamine officials say the county has more shoreline — 42 miles — than any other county along the Kentucky's 255-mile length. A dozen years ago the county put up historical markers along the river and produced a brochure to point out historical sites and natural features.
Reopening the lock would be up to the river authority, which is looking at the potential costs, Graves said.
The river authority charges a tariff or fee for each 1,000 gallons of water drawn from the river. In March the authority raised its tariff from 6 cents to 13 cents per 1,000 gallons to help pay for the Dam No. 8 work plus the repairs to locks 1 and 2 at Carrollton and Henry County, respectively. Water utilities pass on the costs to their customers.
The Dam No. 8 project is the latest in a series of dam improvements on the Kentucky River. The new Lock and Dam No. 9 at Valley View was done for $14.9 million.
In 2011, the river authority also replaced Lock and Dam No. 3, north of Frankfort in Owen County, which holds another pool that augments Lexington's water supply. (The Kentucky General Assembly paid for that project: the river authority has debt service only on dams 8 and 9.)
Next year, design will begin on the replacement for Dam No. 10 at Boonesborough. If all goes well, construction could begin in 2015.
The 14 dams of the Kentucky River navigation system were built from 1836 to 1917. Their primary purpose was to bring coal out of Eastern Kentucky.
By the time the last dam was completed near Beattyville in Lee County, the railroads had reached the region, and not much coal ever moved on the river.
Greg Kocher: (859) 231-3305. Twitter: @heraldleader.