The project by Toyota Motor Mfg., Kentucky Inc., will convert landfill gas, which is normally burned off as waste, to electricity and transfer it to its assembly plant in the town of Georgetown.
To get the electricity from the landfill to the plant nearly seven miles (11.3 km) away, Toyota turned to G&W Construction to install transmission lines. The utility contractor had to drill and trench through hard Kentucky limestone to get the job done, but owner Darrell Alderman says it was well worth the effort in order to be part of a project with a major company that will help the community and the environment.
“That makes it that much more exciting to work on it,” he says. “It’s great to be working on a green project where you know that this energy is not just burnt off and wasted but is going to be used to create electricity.”
Gas Becomes Electricity
As solid waste decomposes, a gas that is roughly half methane and half carbon dioxide is produced. The gas often is flared off at landfills.
Landfill gas can lead to smog, harms the atmosphere and contributes to climate change. In many cases, however, it does not have to be flared and can instead be captured and converted to energy.
As of March, there were 645 operational landfill-gas energy projects in the United States, according to the U.S. Environmental Protection Agency, adding that another 440 landfills were candidates and would produce enough electricity to power nearly 512,000 homes. The agency calls using landfill gas for energy a “win/win opportunity” that destroys methane, generates renewable energy, reduces air pollution and creates jobs.
The Central Kentucky Landfill in Georgetown, which is just outside Lexington, is one of the latest operations to accept that win-win premise. Toyota teamed up with landfill owner Waste Services of the Bluegrass on the landfill gas-to-energy project.
The Georgetown facility is Toyota’s largest vehicle manufacturing plant in North America. It is 7.5 million sq ft (696,773 sq m), sits on 1,300 acres (526.1 ha) and employs more than 7,500 people. Last year, it produced its 10 millionth vehicle since opening in 1988.
Toyota reports that the landfill gas system will generate 1 megawatt of electricity an hour, which is about what it takes to power 800 homes. In actual use, the electricity will power the production of 10,000 vehicles a year. Also, greenhouse gas emissions from the landfill will be cut by as much as 90 percent, the company says.
“As a corporate citizen of central Kentucky, we are committed to smarter and better ways of doing business to enhance our community and environment,” says Todd Skaggs, CEO of Waste Services of the Bluegrass, in a news release. “We look forward to being a partner in Toyota’s sustainability efforts.”
Once finished, a network of wells at the landfill will collect and prepare the gas, which will be used to fuel generators to produce electricity, according to the news release. Underground transmission lines will then carry the electricity to the Toyota plant to the south.
‘Heavy Artillery’ Installs Conduit
G&W Construction was tasked with installing those lines over 35,000 ft (10,668 m). The company, located about an hour’s drive east of Georgetown in the town of Morehead, started work in December and finished the following spring.
The specs from Toyota called for the use of horizontal directional drilling on about 23,000 feet (7,010.4 m) of the installation, most of it in residential neighborhoods. The rest was installed by a track trencher in a rural setting.
The crews were pulling three 2.87-in. (7.3-cm) conduits with the electric transmission line in them. The HDD work called for bores with a diameter of 7.5 in. (19.1 cm) ranging from 1,000 to 1,500 ft (304.8 to 457.2 m) in length, and a minimum cover of 48 in. (121.9 cm). With the track trencher, they were cutting 48 in. (121.9 cm) deep and 14 in. (35.6 cm) wide.
Georgetown is in north-central Kentucky, which is notorious for its limestone. The rock is hard and takes more time to cut through, and it can be rough on equipment. Alderman says there was a relatively thin layer of clay on top and then the crews had to work through limestone of around 12,000 psi (827.4 bar).
“It was pretty much a no-brainer that we were going to have to have some pretty heavy artillery to get this in,” Alderman says.
G&W Construction used two Vermeer D100x140 Navigator horizontal directional drills and a Vermeer T655 Commander 3 tractor with a trencher attachment. Two HDD crews operated simultaneously and leapfrogged each other as they completed bores.
They were able to bore 2,000 to 3,000 ft (609.6 to 914.4 m) per week during the winter.
Because of the limestone, they used a 5.75-in. (14.6-cm) diameter hammer drilling system for the pilot bores and did not need to backream. The hammer system can fracture rock and made a large enough hole that backreaming was not required.
“The limestone is layered, and in layered rock the steering is a little more of a challenge,” Alderman says. “So we just drilled it and hooked to the conduit and pulled it back, which really saved time.”
For its drilling fluid needs, the company used a Vermeer MX240 drilling fluid system and a Vermeer by McLaughlin vacuum excavator.
On the open-cut portion of the job, the trenching crew installed an average of about 500 ft (152.4 m) of conduit a day. They used a chevron formation for the trencher teeth to cut through the limestone. It’s a more versatile pattern in solid or chunky layers and one G&W Construction previously had success with in similar conditions, according to Alderman.
Meeting Industry Challenges
Alderman says the project was an example of how important equipment is in today’s underground industry. G&W Construction has been in business for half a century, since Alderman’s father started the company to construct commercial buildings. These days, it specializes in underground utility installation, and Alderman says increased competition is shaping the industry. That makes bidding on jobs a bigger challenge than ever, and Alderman says a successful company must have the right equipment to work as efficiently and as productively as possible.
The Toyota job had tough ground conditions with the limestone and a tight deadline, and G&W Construction worked for a major company on a cutting-edge project that will turn landfill gas into energy.
“We were proud to be selected by Toyota to do this job,” Alderman says. “Then the production we were getting made it that much sweeter. It was just a real neat challenge.”
Gregg Hennigan is a features writer for Two Rivers Marketing, Des Moines, Iowa.