In the Chugach Mountains, about 1,310 ft. (399 m) above the city of Valdez, Alaska, Hitachi excavators are helping to deliver sustainable solutions by working on a hydroelectric site.
Four ZX470LC-5 excavators, a ZX50U-5 and a ZX85USB-5 are moving earth on the Allison Creek Hydroelectric project, which is spearheaded by McMillen Jacobs. The environmental, engineering and construction firm provides comprehensive technical capabilities on a wide range of water resource, hydropower, dams, transportation and tunnel projects, using design-bid-build and design-build delivery methods.
McMillen Jacobs’ Hitachi excavators are moving about 400,000 tons (362,873 t) of earth for the project, which primarily includes creating a structure to divert water from Allison Creek into a penstock that will carry the water 7,000 ft. (2133.6 m) down a mountain to a self-running powerhouse capable of producing 6.5 MW of electricity per hour for consumers.
As a former operator, Cody Wilson, McMillen Jacobs project superintendent, knows how equipment can make or break project progress, and he’s been pleased with the Hitachi excavators’ performance.
“The cab is comfortable for the operators,” Wilson said. “You sit in the cab 10 hours at a time; you need to be comfortable. It’s little things, like if windows fog up because of vent placement, that really matter. Hitachi is very user-friendly and designed well. When your operators are comfortable, they’re happy and they can work.”
Along with other tasks, the ZX470LC-5 excavators are hammering rock, digging dirt and placing 171 sections of approximately 40-ft. (12 m) pipe, which weigh about 9,600 lbs. (4354 kg) each, for the penstock. Each ZX470LC-5 is outfitted with single steel grousers for added traction in the mountainous terrain.
“The 470 has good power,” said excavation foreman Jacob Macial. “We’ve got tough conditions here in Alaska, and the Hitachis can handle them.”
The company used the ZX50U-5 to remove about 1,000 cu. yds. (764.5 m3) of shot rock from the tunnel sill in order to bury the penstock pipe below grade of the 768-ft. (221 m) access tunnel. Wilson said the size of this tiny titan was critical for completion of the penstock work inside the 16-ft.-wide (4.9-m) by 16-ft.-tall (4.9-m) tunnel.
“It was the biggest machine we could fit in the tunnel that could turn around,” Wilson said. “The zero tail swing was crucial.”
In addition to site work and construction management for the project, McMillen Jacobs is also managing more than 15 environmental plans – from avian protection and water quality sampling to erosion control and bear safety. Yes, it’s not unusual to come across bears on jobsites in Alaska.
Along with bears, it’s also not unusual to face challenges of tough conditions and remote site locations. And Hitachi dealer Construction Machinery Industrial (CMI) understands how to best support customers up against the elements.
“Working in Alaska is a challenge,” said Travis Shelton, McMillen Jacobs project manager on the Allison Creek Hydroelectric Project. “We keep a full-time mechanic on site, and the CMI guys are good about responding with product support.”
Estimated to be completed this year, the project is expected to save burning 700,000 gallons (2,649,788 L) of fossil fuel and eliminate 12,000 tons (10,886 t) of carbon dioxide annually. Wilson said he’ll miss taking in the panoramic views every day on site, but he’s looking forward to seeing the Hitachi excavators finish the project.
“We’ve had good luck with Hitachi,” Wilson said. “The reliability’s been very good throughout this project.”
McMillen Jacobs is serviced by Construction Machinery Industrial LLC, Anchorage, Alaska.
Allison Creek Hydroelectric Project Stats
- Powerhouse access road
- 0.5-mi. (0.8-km) lower-access road
- Access tunnel: 768 ft. (221 m) long; 16 ft. (4.9 m) wide and 16 ft. (4.9 m) tall
- 2.1-mi. (3.4-km) upper-access road
- In-stream diversion and intake structure requiring approximately 1,200 cu. yds. (1,560 m3) of concrete
- 7,000 ft. (2133.6 m) of 36-in. (915-mm) and 40-in. (1,015-mm) penstock pipe
- 60-ft.-by-70-ft. (18-m-by-21-m) powerhouse building with a 70-ft.-long concrete tailrace
- 6.5 MW turbine package
- New substation
- 3.5 mi. (5.6 km) of high voltage transmission line connecting new power generated from Allison Creek to existing Dayville Substation