Wednesday, Jan 11, 2012, 05:26PM CST

By Mark Lisheron

City of Austin officials wildly inflated the volume of plastic bags in Austin’s litter stream and the cost to dispose of them, based on a misreading of a key report cited by the officials, one of the authors of the report told Texas Watchdog this afternoon.

It was unclear how the error, an extrapolation more than three-and-a-half times larger than it should have been, will affect a proposed ordinance that would make offering disposable shopping bags of plastic or paper

a misdemeanor

in Austin beginning in January of 2013.

The city’s Solid Waste Advisory Commission is

expected to consider

the ordinance at 6:30 p.m. tonight in Austin’s City Hall. Should an ordinance be approved, the City Council is expected to vote on it sometime in March.

As of 4 p.m. Bob Gedert, director of Austin Resource Recovery, was unable to respond to Texas Watchdog’s questions about the calculation he used in

the report upon which the disposable bag ban is based.

He was, however, expected to address them at the commission meeting, his spokeswoman, Lauren Hammond, said.

The reason Gedert could not make an estimate of plastic bag volume or cost in Austin based on the report he cited was the figure for plastic bag volume in the U.S. was not in the report, Steven Stein, an

environmental scientist

and co-author of the 2009 study of litter in the U.S., told Texas Watchdog.

The Keep America Beautiful litter study listed the top 10 sources of visible litter on American roadways. Cigarette butts were responsible for 36.3 percent of the litter. Plastic bags, at .6 percent did not make the top 10 list or the study, Stein said.

“We had, like, 60 categories, and we weren’t going to include them all,” Stein said. “Because plastic bags made up such a minute portion of the waste stream we didn’t include it.”

In his report to the City Council in January of 2011, Gedert cites Stein’s study and uses a 2.2 percent figure, which corresponds to a type of litter Stein called Other Plastic Film . This category refers to agricultural plastic like the sheeting wrapped around big round bales of hay.

“That’s the only place I can think of where he might have gotten the 2.2 percent,” Stein said.

“You have overstated the amount and cost impact of plastic bags by about 366 percent,“ Stein wrote. “Additionally, since retail plastic bags only constitute a portion of the study’s plastic bag category (dry cleaner bags and trash bags are also in this category), even 0.6 percent for retail plastic bags is an overstatement.”

“Specifically, page three of your memo indicates that plastic bags constitute 2.2 percent of litter. The

2009 National Litter Study

found that plastic bags of all types comprise only 0.6 percent of litter. Percentages for categories that constituted minute portions of roadside litter, such as plastic bags, were not addressed in the

2009 National Litter Study.”

“Thus, the wrong data point was used in this memo’s analysis. The mix-up may stem from Figure 3-3 (Top 10 Aggregate Litter Items, All U.S. Roadways) on page 3-3 of the KAB

2009 National Litter Study

. That table lists “Other Plastic Film” as 2.2% of all litter. Note that this category specifically excluded plastic bags.”

Stein said he has so far not heard from Gedert, before or after his letter.

“Regardless of this position you take on this issue, what is of consequence is that you dig deep enough to make sure you have the correct data to base your assumptions on,” Stein said. “I think it was an honest mistake that I would have been happy to point out to him. But I think the public in Austin ought to know about it.”