Green digest

Special muffler reduces air pollution at Crosstown site

Hennepin County worked with Ames Construction to install a special muffler designed to reduce air pollution on one of Ames’ off-road cranes at the Crosstown project site.

The Donaldson diesel oxidation catalyst (DOC) muffler is designed to reduce particulate matter emissions from 15 to 30 percent, according to a Hennepin County newsletter.

Particulate matter is a mixture of very small particles and liquid droplets that are comprised of acids, organic chemicals, metals, soil and dust particles.

From June through December 2007, crews operated the crane for more than 1,000 hours.

The muffler reduced particulate matter emissions an estimated 12 to 24 pounds during that seven-month period, according to Environmental Protection Agency (EPA) estimates.

The crane outfitted with the muffler was also used during the construction of the Midtown Greenway Bridge over Hiawatha Avenue, according to the county newsletter.

City observes ‘Earth Hour’

For one hour on March 29, the city turned off all nonessential electricity in city buildings in an effort to symbolize Minneapolis’ commitment to fighting global warming.

Several other buildings also participated in the “Earth Hour” program, including the Wells Fargo Center, IDS Center, Thrivent Financial, U.S. Bancorp, and the historic State, Orpheum and Pantages theaters.

The city observed the “Earth Hour” from 8–9 p.m.

“This is about more than just one hour or just one day,” said Mayor R.T. Rybak, in a prepared statement. “If we can make a difference in one hour, imagine how much good we can do for our environment if we practice energy conservation every day. As city government, there are many ways we’re working to be more green, but this is a great reminder that each of us can play a part in fighting global climate change by making smart energy choices in our daily lives.”

Minneapolis is one of the first cities in North America to participate in the “Earth Hour Program,” which is organized by the World Wildlife Federation. The first “Earth Hour” was held in Sydney, Australia, in 2007.

According to a city news release citing the state statistics, electricity use in Minnesota accounts for 35 percent of greenhouse gas emissions.

For more information on the city’s efforts to improve the environment, go to

Spring street sweeping begins

City crews are scheduled to sweep all 1,100 miles of the city’s streets through mid-April.

Temporary “No Parking” signs will be posted on affected streets 24 hours before sweeping begins. When a block is being swept, parking will be banned from 7 a.m.–4:30 p.m. Motorists who fail to observe the ban will be ticketed and towed to the Minneapolis Impound Lot.

To check out when crews are headed to your block, go to

Street sweeping helps prevent leaves and debris from clogging storm drains and polluting the city’s lakes and rivers.

Reach Sarah McKenzie at [email protected] or 436-4371.