Steve Roberts, The Beaver Excavating Company photo
The onsite waterline system consists of more than 6,000 ft. (1,828 m) of 72-in. (182.9 cm), pre-stressed concrete pipe.
The Beaver Excavating Company completed its second year of work on the $77 million Columbus Upground Reservoir in 2012 in Richwood, Ohio — the largest upground reservoir under construction in the United States.
“We’re using more than 100 pieces of heavy earthmoving equipment and have 180 Beaver personnel on site on the largest single-volume earthwork project in the company’s 60-year history,” said Beaver Senior Project Manager Steve Roberts.
It’s the longest dam in Ohio and the largest reservoir project in the nation, and perhaps the world, that features a geo-synthetic liner system comprised of an 18 in. (45.7 cm) layer of compacted clay, covered with a polypropylene geomembrane, a cushion geo-textile and then finally an 18 in. layer of protective cover soil, according to Roberts.
“The geo-synthetic liner was added because of the site’s potential for sinkholes due to the area’s Karst geology,” he added. “The underlying limestone bedrock has the potential of being eroded by water creating the possibility of underground openings and caverns.”
The project was awarded to Beaver by the city of Columbus and is the first of three planned upground reservoir projects recommended in the Columbus Department of Public Utilities’ Water Beyond 2000 Feasibility Study.
Work on the three-year project began in January 2011. When completed in October 2013, it will cover 850 acres (344 ha) and hold more than 9 billion gal. of water. Thus far 8.5 million cu. yds. (6.5 million cu m) of earthworks and 600 acres (243 ha) geo-composite liner system have been installed.
The work began with the reservoir dam — 5 mi. in length, 45-ft. (13.7 m) high — which surrounds the entire project. It also involved the removal of a 5-mi. (8 km) area of topsoil, 56,000 ft. (17,068.8 m) of existing agricultural field tile, constructing 10 mi. (16 km) of 15-ft. (4.6 m) deep by 20-ft. (6.1 m) wide cutoff trenches to prevent area field drainage and ground water from compromising the reservoir walls, and a dewatering system installed prior to construction to lower the areas artesian conditions.
Site work for the reservoir’s dam required 110,000 tons (99,790 t) of sand for a blanket drain; five million cu. yds. (3.8 million cu m) of structural fill; 280,000 tons (254,012 t) of rock shore protection, topsoil, and seeding; and 55,000 ft. (16,764 m) of security fencing.
“For much of the 2012 season we averaged 320,000 cubic yards of earthwork per-week working single shifts,” said Beaver Commercial Division Vice President Pat King.
Another of the project challenges was constructing the 800 acre (324 ha) of geo-synthetic liner system. This required innovative planning in terms of scheduling, soil borrow and construction materials. The work was divided into 24 sub-projects called panels, each comprised of a clay liner, poly-propylene liner, cushion geotextile and protective cover — they are all layered components.
“Close timing was essential to keep the process synchronized,” said Roberts. “The liner system required 2 million cu. yds. of clay liner, placing 800 acres of flexible polypropylene liner, another 800 acres of cushion geotextile and finally covering the liner system with 2 million cubic yards of protective cover. There will be about 375 mi. of seaming to attach the polypropylene geomembrane into one solid 800 acre sheet.”
Environmental Protection Inc. was responsible for the synthetic liner panel fabrication and placement. Other subcontractors and consultants included Contract Dewatering, McKinney Drilling, Atlas Electric, CTL Engineering, Great Lakes Fence, Woodland Acres, The Shelly Company, and Mohawk Rebar.
Beaver is installing the inlet and outlet structures and the piping system to fill and empty the reservoir.
“The project requires about 2,000 cubic yards of structural concrete.” said Roberts. “The outlet structure will have six automated gate valves to control water flow and its foundation is constructed on 18 caissons drilled into the limestone bedrock.”
The onsite waterline system consists of more than 6,000 ft. (1,828 m) of 72-in. (182.9 cm), pre-stressed concrete pipe. Other necessary infrastructure includes more than 7,000 ft. (2,133 m) of stormwater sewer, 5 mi. (8 km) of blanket drain outlet pipe, a boat ramp and an overflow structure.
The project is extremely weather sensitive, according to Beaver’s Onsite Project Manager Jeremiah Johnson.
“We went from one of the wettest years on record to one of the hottest,” he said. “From the nearly 60 inches of precipitation in 2011, to the more than 50 days with temperatures of 90 plus in 2012 and yet we finished over 55 percent of the embankments, which by itself is incredible under ’normal’ circumstances.”
The heat also impacted the building materials, especially the liner material.
“Temperatures were recorded as high as 140 degrees,” said Roberts. “Several safety measures were implemented, including worker training and continuous heat index monitoring, an air-conditioned mobile room, canopies for shade, cooling vests, mandatory breaks, shortened work days, water and ice chests, etc.”
Beaver is proud that no injuries were recorded in 2012, a year that logged nearly one million man hours worked, said Roberts.
At any one time, 10-plus Beaver crews and four or more subcontractors were at work on the site.
More than 100 pieces of heavy equipment and machinery were employed on the project and like the men, had to operate efficiently and handle weather extremes.
“The biggest thing is coordinating all the equipment and the people to be where they need to be so they’re out of each other’s way,” said project lead superintendent Mark Kopp. “It came down to communicating from what we had to do from my standpoint, to the foremen to the people.”
Beaver’s fleet included vehicles such as several water trucks for dust control, pickup trucks for supervision and labor transport, onsite lube truck for maintenance, lowboys for moving machinery, and wheel loaders for material placement. Also employed were a variety of machinery such as Cat 773 trucks, Hitachi and Komatsu 10 cu. yd. (7.6 cu m) excavators, Cat Challengers, Cat 631 scrapers, D6 thru D10 size dozers, and numerous Cat, Komatsu, and Deere excavators.
The worksite provides ample space to set up yards for materials and for Fleet Manager Hugh Brown and Onsite Master Mechanic Brian Garren to set up fuel depots, storage for spare parts, onsite maintenance shops, and offices to help manage the fleet.
In addition to its existing fleet and equipment, Beaver purchased new items from Ohio CAT, Columbus Equipment Co., and Murphy Tractor, and rented from the same companies to fulfill missing equipment needs.
Beaver’s maintenance team is keeping a close eye on ensuring that unexpected breakdowns do not occur and is monitoring and logging operating hours via GPS tracking systems mounted on the equipment.
“We know hours and location, along with any other issues on the equipment in an instant,” said Brown. “And with open communication between the shop and field, the field was inconvenienced as little as possible, while still ensuring proper maintenance was performed. On a project this equipment intensive, we relied on the GPS, but first and foremost the communication was top notch between operators, supervision and maintenance personnel, and vice versa. Everyone deserves recognition on a project this size.”
Garren usually has three mechanics on site (including himself) and can secure more when necessary.
“Keeping everything running is a daily challenge,” he said. “The average repair time varies by breakdown — if we have the parts on hand, downtime may be two hours. Major repairs, like rebuilding an engine, could take four or five days. Communication with all the mechanics and job superintendent Mark Kopp was the key. I’ve learned the importance of being organized and planning repairs based on the crews’ needs. Repairs were delegated to the technician with the appropriate strength.”
Because there are multiple numbers of vehicles, if one breaks down, another can fill in and with others being multi-purposed, Beaver has been able to stay on schedule.
“This is a demanding project,” said Johnson. “The team that has managed this project was hand-picked, and we have a core group of guys down here that work on this project on a daily basis. What has made this project successful is the people.”