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Industry calls for delay in transition as economy hits projects and budgetsA number of local contractors using backhoes or other large off-road equipment are hoping state air-quality regulators late this year push back the cleaner-burning diesel deadline by several years, based on new figures for soot and ozone-forming emissions that are roughly 20 percent of those used in adoption of the rule three years ago.

The new estimates by staff of the California Air Resources Board come close to findings in an April construction industry-funded study by Sierra Research, according to Mike Kennedy, general counsel for trade group Associated General Contractors of America.

Air board staff unveiled the revised inventory of current and projected emissions of soot, called PM2.5, and nitrogen oxide gases, or NOx, from diesel trucks, buses as well as construction and industrial vehicles at five workshops in the past two weeks. Inventories for on-road vehicles were decreased but not nearly as much as for construction vehicles.

"It's a very dramatic difference," he said. "We're talking about much more than a minor mid-course correction."

For example, the 2007 estimate for construction-related emissions of NOx in 2010 was 342 tons per day statewide, while the new inventory of emissions this year pegs it at 75 tons per day. Half the difference came from idled equipment because of the economic recession, and the other half came from more complete fleet activity information air board staff gathered by spring of this year.

A weighted-average third of equipment fleets were operating fewer hours per year than projected in the rule, while two-thirds had fewer vehicles than anticipated, according to materials presented at the workshops.

The state has 32 percent fewer diesel-powered construction vehicles operating one-third to 79 percent fewer hours per year on average than projected for the industry in 2010 when the board adopted the off-road diesel rule in July 2007.

The off-road rule requires engines larger than 25 horsepower to be retrofitted or replaced to reduce emissions of PM and NOx starting this year for large fleets, or those with more than 5,000 total horsepower.

"The industry has been screaming that we want cleaner air, but give us something to work with” and leeway for technology to improve, said John Bly, executive vice president of the Engineering Contractors Association of Northern California. For example, equipment maker Caterpillar recently introduced an engine that would meet the air board's best emissions rating.

Early this year, air board staff stalled enforcement because of state legislation adopted last year as part of state budget negotiations largely granting large fleets a two-year extension because of stalled construction activity. Also, a late 2009 U.C. Berkeley study led by environmental engineer Robert Harley found the emissions estimates in the 2007 rule were 3.1 to 4.5 times higher for PM2.5 and NOx, respectively, than actual industry activity would generate, based on analysis of diesel fuel consumption.

Construction industry trade groups want the air board to delay the forced phase-out of older diesel engines until at least 2016, when off-road emissions are now projected to rise above the original regulatory targets.

"The big picture is that we are looking at offering what relief we can but maintain progress on cleaning up the air," said Kim Heroy-Rogalski, manager of the air board's Off-Road Implementation Section.

In December the air board is set to consider amendments to the off-road rule, including the new emissions estimates.

For more information, visit the board's off-road diesel rule page at www.arb.ca.gov/msprog/ordiesel/knowcenter.htm.

CORRECTION, Sept. 13, 2010: The 2007 estimate for construction-related emissions of NOx in 2010 was 342 tons per day statewide. Incorrect information was provided for the story. Half the difference between the 2007 and 2010 inventories was because of the economic slowdown and the other half was because of more complete fleet activity information gathered through spring of this year, according to air board staff documents.