Reservoir Quenches Thirst of GA Community

Tue August 17, 2004 - Southeast Edition
Kerry Lynn Kirby

At one time, it was merely a stretch of typical rural timberland. But by next spring, 1,466 acres of Henry County, GA, will be transformed into a desperately needed source of fresh drinking water for residents and businesses in the rapidly growing area.

According to Henry County Water and Sewerage Authority, the situation is dire: Using conservative growth estimates, it was predicted the county, a suburb of bustling Atlanta and one of the fastest-growing counties in the country, would run out of adequate raw water supply if a new source was not on line by this year.

Between 1995 and 2001, the authority’s residential and commercial customer base exploded from just more than 19,000 customers to top the 34,000 customer mark, according to the authority’s Web site. And it has grown by about 800 customers since 2001.

Work on the roughly $15 million Tussahaw Reservoir began in August 2003 and is expected to be completed in spring 2005, according to project engineer Garry Garretson, a principle in Stantec.

The new reservoir and the adjoining water treatment facility also under construction will yield 23.6 million gallons of water per day, which should meet the needs of the county until the year 2027, according to the authority.

The contract for the reservoir was awarded to Brad Cole Construction Inc. of Carrollton, GA, the low bidder among a handful of authorized, prequalified contractors, Garretson said.

The reservoir project involves five primary elements: building the main dam, constructing the emergency spillway, building three saddle dams, constructing the primary spillway tower and clearing the reservoir pool, explained Garretson, who is based in the engineering firm’s Macon, GA, office.

A total of approximately 12,000 cu. yds. of concrete will be used on the project, he said.

The reservoir will be created by impounding the Tussahaw Creek. The pool clearing is accomplished using bulldozers with shearing blades.

“They’re basically shearing off the trees at root level,” said Garretson, noting the roots are left to stabilize the basin.

The trees are piled up using backhoes and burned on top of the ground by permit. By early August, Garretson said, the pool clearing was about 75 percent complete.

Only about 15 percent complete, the main dam will be 75 ft. tall, built with approximately 300,000 cu. yds. of earth fill.

The three saddle dams –– small dams filling up low places that are there just for flood events –– will contain a total of approximately 100,000 cu. yds. of earth fill, which is coming from the site, Garretson said.

The emergency spillway, a five-cycle, two-stage labyrinth, is 100 percent complete.

The primary spillway tower, featuring a 78-in. diameter prestressed concrete cylinder (PCC) pipe that has to be in before the creek diversion can take place, is halfway along.

Putting in the conduit provided an expected, but at the same time unknown, challenge, Garretson said.

“We knew we were going to have some rock ... but we couldn’t blast because it was under the main dam,” he said. So crews had to move the rock mechanically using special equipment.

“We knew we were going to encounter it, but rock is something you never know how much you’re going to have until you get down there,” Garretson said.

Fortunately, moving the rock took only an extra couple of weeks, he said.

Brad Cole, president and CEO of Brad Cole Construction Inc., added that the job involves clearing and grubbing about 1,750 acres, all woods.

Cole said his company has had 30 to 35 workers on the job, working a single shift.

Project components include excavation and removal of unsuitable soil; preparation for the foundation of the dam, which involves preparation of rock surfaces and dewatering the foundation so they can excavate in dry conditions; and installation of the principle spillway pipe and other concrete structures that go with the drainage structures, he said.

The concrete labyrinth wall spillway, about 200 ft. wide with 30-ft. walls containing 1,200 cu. yds. of reinforced concrete, is unique to the project.

It calls for more concrete than normally used for dam construction because of the large watershed, or the amount of rainfall that hits an acre of ground draining on a particular basin.

Because there’s so much potential drainage coming into the basin then stopping up, they needed this spillway to prevent a breach of the dam, Cole said.

Cole said almost all of the equipment his workers used on the job belongs to his company.

Caterpillar D6 and D8 were put to work on the land clearing, he said. Caterpillar and Komatsu excavators, including Komatsu PC400 excavators, were used along with Caterpillar 621G and 631G scrapers.

He said his company’s two primary equipment dealers are Yancey Bros. Co. in Atlanta, for Caterpillars, and Birmingham, AL-based Tractor & Equipment Co., for Komatsus.

“I’ve been happy with them for about 30 years. We have a long relationship,” Cole said.

One piece of specialty equipment –– a 200-ton rough-terrain Grove crane — was needed for installation of the 78-in. pipe, Cole said.

It was rented from Southway Crane & Rigging of Atlanta, he said.

Carter Concrete Structures of Stone Mountain, GA, was subcontracted to build three structures on the job: the emergency (or secondary) spillway, the outfall (or riser) structure and the primary spillway, according to Allan Day, project manager of Carter, which started on its parts of the job in September 2003.

The number of workers on the project has varied from 20 to 40, working one shift, he said.

Day said the company has been working on the three structures simultaneously and expects to be finished in September, a little behind the original target of early August.

Rain nearly every day for about three weeks in June is to blame, he said.

Nearly completed, the emergency spillway features walls along the side as high as 25 ft. tall and was constructed using a Conesco Doka Framax wall-forming system. It contains 8,000 cu. yds. of concrete.

Two cranes, a 110-ton Link-Belt and a 40-ton Link-Belt all-terrain, were leased (operated and maintained) from Phoenix Crane Rental Company of Mableton, GA, for that portion of the job, Day said.

Carter is currently working on the outfall structure, which rises a little more than 60 ft. into the air and will contain between 1,200 and 1,500 cu. yds. of concrete.

Its design features a half-barrel bottom for water to flow through and a mushroomed top to provide a work surface area for the sluice gate operators and to support manholes to provide worker access into the riser. The bottom is about 14 ft. wide, and the top is 38 ft. wide.

“This structure presents a very big challenge,” said Day, explaining that the formwork for the first lift of the riser had to be stick-built on the job, though above the first lift they were able to use the Framax.

They’re currently working on the top part of the structure, using the 110-ton Link-Belt crane, he said.

The primary spillway, featuring walls 8 to 11 ft. tall on each side and a long spillway where water will flow back to the creek, is being built using the 40-ton Link-Belt crane and the Framax.

“It’s pretty straightforward compared to the rest of the structures,” he said.

All of the concrete structures, the intake and outtake structures, and the principle spillway pipe must be in place before the river is diverted into the principle spillway, Cole said.

Once the river is diverted, they’ll need to go over and prepare the surface where it was running and put in drainage devices before the entire reservoir can be flooded, he said.

Cole said the job is very close to schedule, maybe slightly ahead, as they’ve been able to make more progress than originally expected.

At this point, he said, it looks like it will be finished around the end of January 2005 instead of April or May.

The Henry County Water and Sewerage Authority actually identified the Tussahaw site a number of years ago and started acquiring the property for the project in the ’90s, said Garretson.

But it took a long-fought court battle to get the clearance to proceed with the Tussahaw Reservoir and Water Treatment Facility, according to the authority, which said the Tussahaw location was deemed the safest, most feasible and cost-effective alternative for expanding the raw water resources of the region.

The project plans also include a proposed 1,045 acres of wildlife buffer and 576 acres in wetland mitigation sites to provide long-term water quality and habitat protection for the environment.

While the purpose of the reservoir is to provide drinking water, Garretson said, “It will double up as a limited recreational use reservoir.”

That means that fishing, canoeing and kayaking will be allowed on the lake, but sailboats and gas motors will be banned to preserve the quality of the water, he said.

The project will provide another benefit besides drinking water and recreation, Garretson said.

The reservoir will be 5 miles upstream of Jackson Lake, which is owned by Georgia Power and has a hydroelectric dam on it. The lake has had a problem with siltation because of construction in the Atlanta area.

“This reservoir will help the Tussahaw arm of Jackson Lake by trapping siltation,” Garretson said. “It will help that situation a lot.

“As far as the construction itself, it’s a pretty remote site, very little contact with the residents out there,” he said.

Cole said he wasn’t aware of the project disrupting any homes, though a couple of county roads had to be raised at the upper end of the lake.

In addition to Henry County, the project has affected Butts County because of the concrete coming out of there, Garretson said. And Butts County has been really helpful in terms of routing the trucks, he added.