Filling up

Features - Mixed C&D Processing

Concrete processor change bolsters quarry reclamation effort in the Los Angeles suburb of Irwindale.

July 10, 2012
Larry Trojak

Quarry and pit reclamation projects are hardly a new concept. For decades, depleted mines, quarries and aggregate pits have been filled in and re-established as land or water recreational areas or commercial development sites. Nowhere, however, is the practice more needed or more appreciated than in the City of Irwindale, Calif. Located in the San Gabriel Valley northeast of Los Angeles, the city is home to more than a dozen massive aggregate pits that sit idle, awaiting purchase and subsequent recovery. At the NuWay Arrow Reclamation Project, one such reclamation effort already underway, the recent purchase of a Genesis Concrete Processor (GCP), is helping boost production and minimize downtime.

Rocking SoCal

Operated by the Environmental Protection division of Waste Management Inc. (WMI), the NuWay Arrow site takes in construction and demolition (C&D) debris, as well as clean fill and other inert waste from area construction companies, independent contractors and the general public and is systematically filling the void left by the quarry operation. According to Nicholas Godfrey, WMI’s operations manager, the quarry once played a valuable role in southern California’s development but has long since served that purpose.

“The material that was mined out of here probably supplied rock for most of the highways in the entire Los Angeles area during the boom years of the ‘50s though the early ‘70s,” he says. “It’s been closed and idle since the 1980s; now we are going back in and filling it. So while this is a land reclamation effort, the site is also an engineered fill, taking in material, downsizing any oversized debris, spreading it and compacting it to certain specifications. That will continue until we are up to street level which is currently about 80 feet up.”

Godfrey says incoming volumes can vary greatly, largely dependent upon the economy and, by extension, the amount of development going on. “So we can bring in as much as 2,000-3,000 tons a day, or have that dwindle to 3,000 tons a week. It really varies, but we probably average about 12,000 tons a week across the scales,” he says.

Making a change
Because so much of the material taken in at NuWay Arrow is concrete debris, larger pieces must be downsized to remove rebar and make them spreadable by dozer prior to compaction. For years, WMI had relied upon a pair of excavator-mounted hydraulic processors to do that. However, concerns about increased downtime and the maintenance needed to keep the attachments operational prompted a look for alternatives.

“This is a challenging and demanding environment for any tool,” says Godfrey. “Keep in mind that we process some high-strength reinforced concrete with those tools and work 16 hours a day, six days a week, so it’s definitely hard on equipment. But our maintenance people were spending what they felt was far too much time and money keeping the older processor running, so they researched what was out there and decided to go with the Genesis Concrete Processor to replace one of those older units.”

That decision was a sound one, according to Clarence Thigpen, the site’s maintenance supervisor. On average, he says, his people were welding each of the older processors about three times a week. Despite having the GCP 410 for six months, they have yet to do any welding on it.

“There are a lot of things that are just better by design on the new Genesis processor, so the wear characteristics are much, much better,” says Thigpen. “All the way from the bushings down to the jaw, it seems to have been better thought out. On our other processor we purchased 1.25-inch plate steel, cut it and welded it to each side of the tool; we essentially rebuilt it just to stand up to the daily use. The Genesis hasn’t needed anything other than normal maintenance. And performance-wise it’s just as impressive; it crushes anything that will fit in its jaw.”

Designed for performance
The GCP 410 in use at NuWay Arrow is mounted on a Cat 320C and offers a range of minimum-maintenance features that have benefited Thigpen and his crew. These include a one-piece bolt-on replaceable tooth bed and a one-piece lower wear pad which protects the stationary jaw. Both features eliminate the need for build-up and hard-surfacing. Even the rebar cutting blades, critical for dealing with reinforced concrete, are four-way indexable for maximum life. A large-bore cylinder provides more power than its larger counterpart in use at the site and does so without the need for an intensifier.

“The new attachment has made a definite impact on our operation,” says Godfrey. “While the Genesis tool is a bit more powerful than what we’ve had, that’s not its real value to us. More important to us is the degree to which we’ve reduced maintenance-related downtime—simply put: it’s there when we need it. The other processors demanded five or six hours of welding every week, and we are just not set up to accommodate that workload. Our mechanic rotates between this site and two others and simply doesn’t have that kind of time.”

Onward and upward

Back in the pit, trucks continue to dump material, bringing the quarry floor slowly but steadily upward. The procedure is fairly straightforward: having already crossed the scales, a truck enters the pit, dumps the load, WMI personnel size-reduce all the material (extremely large pieces are first downsized with a hydraulic breaker), pull out any rebar or trash, push it with a dozer, mix it with water, compact it and then have it tested to meet specs. Removing the rebar is important for a number of reasons, says Godfrey.

“First of all, it is a recyclable material so there is nothing to be gained by burying it. More importantly, however, mixing it with the dirt, concrete, brick and stone only increases the risk of voids occurring—something we simply can’t have. So our operators are very good at crushing the reinforced concrete, pulling out whatever rebar is present and setting it aside for removal.”

Godfrey says they still have a few years left at the NuWay Arrow site before it is filled to street level and ready for redevelopment. “You look at this massive pit and it’s hard to believe it will ever be filled, but having done others, we’ve seen how quickly that can happen. In the meantime, we are really pleased with the way things have turned out and welcome the new level of efficiency we get with the Genesis Concrete Processor. It’s become a very nice addition to this project.”


This article was submitted on behalf of Genesis Attachments, Superior, Wis.