One of the trucks on display at World of Concrete in 2012 was a red Kenworth W900S with a red and white striped McNeilus Bridgemaster mixer body. The colors and configuration are quite familiar around Chicago, but not often seen in Las Vegas.

It’s the signature color scheme of Ozinga Ready Mix Concrete, Chicago’s only locally owned ready mix producer and — with 450 ready-mix trucks and 75 support vehicles — one of its largest. The Kenworth was one of the first of Ozinga’s current fleet of 40 mixers fueled by compressed natural gas (CNG). According to Tim Ozinga, director of corporate communications, the fleet will be 100 percent CNG-fueled by 2020, including all support vehicles.

From coal to alternative fuel

Founded in 1928 by Martin Ozinga Sr. and Bill Conrad as the Conrad and Ozinga Coal and Coke Company, the company upgraded from horse power to horsepower with its first motor truck the following year. Soon after, Ozinga bought out his partner. He turned it over to his three sons in 1942. The company suspended operations during World War II, as all of the Ozinga sons enlisted in the armed forces.

Upon their return in 1946, the brothers shifted the company’s emphasis from fuels to building materials. It grew with the postwar building boom. The distinctive red and white striped mixer drums owe their design to the stripes on the American flag that the brothers served. They kept their father’s dedication to providing quality products and services to customers and community alike.

Fast forward to 2011 and the opportunity to evaluate and perhaps pioneer the use of natural gas as an alternative vehicle fuel. The operating economics looked good on paper, and converting to domestically produced gas reduces our dependence on imported petroleum. Natural gas also reduces greenhouse gas emissions by 23 percent with 80 to 90 percent less carbon emissions. As an added benefit, the CNG Cummins-Westport engine is up to 90 percent quieter than diesel—an important consideration in urban Chicago.

Investing in efficiency

Ozinga hadn’t bought trucks since 2006, so by 2011 it was time to start replacing them. Now run by the fourth generation of Ozingas, the brothers and their cousin decided to evaluate CNG. They worked closely with Kenworth, McNeilus, and Cummins-Westport on the optimal specifications, and bought 14 new trucks in November 2011. Power from the 8.9-liter ISLG engines is 320 hp with 1000 pound-feet of torque. Fuel capacity, measured in diesel gallon equivalents (DGE) is comparable to the trucks that were replaced.

“Before we could put the trucks into service,we needed to put in a refueling system,” says Tim Ozinga. “Then we had to train our drivers on operating it, and all the safety procedures.” After contracting with People’s Gas to supply the fuel, Ozinga purchased the refueling system to supply the trucks. High-pressure storage tanks were installed, along with a compressor to bring pressure up to 3500 pounds per square inch (psi), storage pressure for CNG. To get the power required to drive the compressor, Ozinga had to install a dedicated transformer next to the compressor.

The weights of the CNG and diesel trucks are within 1000 pounds of each other,mostly due to the weight of the CNG fuel tanks. The producer’s typical loads still run 8-1/2 to 9 yards. The CNG trucks are averaging five to seven loads per day, and three to five loads to rural locations. “To help, we added time-fill fueling in our Mokena (Ill.) location and we’ll be expanding CNG to northwest Indiana,” Tim Ozinga says.

For 40 CNG trucks currently in service, the producer has 30 time-fill units in operation, along with three fast-fill pumps. Trucks using time-fill refueling are left overnight, while the fast-fill pumps can refuel a truck in as little as 10 minutes. Fast-fill can bring the tanks to between 85 and 90 percent of capacity; time-fill takes them to 100 percent.

At Ozinga’s Chinatown facility, a driver brought a truck in to his assigned parking space and hook uped to the time-fill connection. It took longer to put on the required safety gear than to actually connect the high-pressure hose. The whole process took about 10 seconds. Then the driver went home.

If a truck runs out of CNG on the road, it can be refilled from any other CNG truck in the fleet. A hose carried on each truck connects to the refueling fitting. Within a short time, depending on gas pressure in the donor truck, the two trucks will equalize fuel pressure and each will have half the range that the donor truck started with.

Tim Ozinga also refills his dual-fuel (gasoline and CNG) Chevrolet support vehicle here. He pulls up to the fast-fill pump, connects the air-tight safety fitting and starts the pump. In minutes, the CNG tank was full. He switches seamlessly between CNG and gasoline, then back again. It can be switched manually or, if one of the tanks runs out, automatically.

Ozinga’s fast-fill pumps also refuel selected customers who are contracted to use the system. This builds both volume and goodwill, and helps the producer amortize its investment.

In February,diesel cost $4.15 per gallon in the Chicago area, while CNG was at $2.56 per diesel gallon equivalent. That’s $1.59 less per gallon,or 38 percent direct fuel savings.

A new maintenance routine

There are also maintenance differences. The change interval for fuel filters, for example, is extended to 1000 hours, compared with only 400 hours with diesel. The producer conducts oil drain intervals according to the engine maker’s recommendations. “We do have to use a special oil –Chevron Delo 15W-40 for natural gas,” says Pete Huisenga, Ozinga’s equipment manager. “It’s not cross-compatible with our diesels, so until the changeover is complete, we’ll have to carry two oils.”

Huisenga changes spark plugs at 1500 hours and runs the overheads (checks valve adjustment) at 2000 hours, compared with about 4000 hours for the diesels. “One nice thing about our CNG trucks is they only have a diesel oxidation catalyst (DOC) and it requires no maintenance,” he says.“There’s no regeneration because there’s no diesel particulate filter (DPF), and no diesel exhaust fluid (DEF) to keep full because no selective catalytic reduction (SCR) system is needed. The exhaust stacks are so clean, you can run a white glove on the stacks and it will come out without a trace of soot.”

Any way you look at it—from fuel cost to operating economy to environmental responsibility—Ozinga’s switch to CNG power is paying off. This is why the producer is on target to have all 500-plus ready-mix trucks and support vehicles running solely on CNG by 2020. TCP

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Paul Abelson writes the regular Fleet Factors column for TCP. E-mail