Little comes easily for Alaska contractors. Beyond harsh sites and weather conditions that continuously put men and machines through stiff tests, materials themselves are hard to come by.
One Alaska contractor who has specialized in challenging projects over the last 25 years is Osborne Construction Co. Many of Osborne’s projects are located in remote areas, and these projects require extensive planning and the ability to coordinate difficult logistical issues.
After using the Allu D-Series DH-4-27-60 screener crusher attachment for a job in 2010, Osborne’s representative attended ConExpo-Con/Agg 2011 and purchased one from Allu Group Inc. Osborne planned to attach the screener crusher to its 60-metric-ton John Deere 600C LC excavator.
“To date we’ve already used the Allu attachment on three jobsites and are getting ready to use it on a landfill job coming up,” says Don May, Osborne’s civil manager. “At each jobsite it has helped us overcome challenges quickly to get the job done on schedule.”
One of the advantages of the screener crusher is contractors do not have to set up a big operation for screening and loading, May says.
“We just attach the Allu and get the job done,” he says. “We were direct-loading 40-ton [articulated] trucks on one of the jobs and were getting 300 to 360 tph of screened material. Having as small of a footprint as possible is important to us, and this one piece of equipment has allowed us to save extra production equipment and man hours.”
Foundations for military housing
Contracted to build 303 units of military housing at Joint Base Elmendorf-Richardson (JBER) in Fort Richardson, Alaska, Osborne Construction Co. quickly discovered that the onsite material it was using under the concrete slab contained cobbles measuring 2.5 to 15 in. in diameter in the raw material.
Osborne built the second phase of housing near the site from 2004 to 2006, and it learned from its experience there come phase No. 3.
“On phase [No.] 2 we ran into poor concrete yield – 15 to 20 percent off from theoretical yield projections because the cobbles were causing the edges of the areas excavated for the thickened edge slab to collapse,” May says. “For phase [No. 3] we considered using more concrete but it was much cheaper to screen the top 3 ft. of under-slab material.”
Osborne started the job by screening 140,000 yds. of minus-2.5-in. material with an Allu screener crusher attachment, rejecting cobbles ranging from 2.5 in. to 15 in.
To keep material in spec and retain good foundational quality, Osborne brought in the Allu screener crusher attachment to screen the cobble material for the slabs.
“Once we screened the bones, the yields came back to within a couple percent of what the theoretical yield projected,” May says. “We had great success not having the bigger rock there.”
In addition to saving money using the onsite material, Osborne was able to continue on schedule with the job because the cobbles were being used for construction roads and in the waste fills to keep the trucks from getting stuck in the mud, May adds.
Railroad extension
Osborne also put the Allu D-Series DH-4-27-60 screener crusher to work while building a railroad extension in September 2012. On that job, Osborne’s crew was using a ripper bucket on its John Deere 600C LC, loosening to a depth of 6 ft. for a length of about 3,000 ft. after running into frozen material.
“The material made spec, but it was full of frozen chunks,” May says. “Normally all the material would have been hauled off and replaced. Instead, we ran the material through the Allu attachment, screened off the big stuff and reused the material in place. Everybody was really happy.”
According to May, specializing in challenging projects requires extensive planning and the ability to manage difficult logistical issues. So finding that piece of equipment that makes a company’s job easier – and finding equipment that can be used on a variety of jobs – makes planning much easier.
“The Allu attachment fits this criteria,” May says. “At each jobsite it has helped us overcome challenges quickly to get the job done on schedule without setting up a big operation. I have no doubt it is a piece of equipment that will be frequenting our upcoming projects.”