Featured Research

from universities, journals, and other organizations

Natural Approach To Cleaning Up Toxic Freeway Runoff Urged

Date:
April 3, 2003
Source:
University Of California - Los Angeles
Summary:
Taking a clever, low-cost and natural approach to the problem, UCLA researchers hope to prevent storm-water runoff from washing thousands of pounds of pollutants into the ocean each time it rains.

Taking a clever, low-cost and natural approach to the problem, UCLA researchers hope to prevent storm-water runoff from washing thousands of pounds of pollutants into the ocean each time it rains.

When the rain begins to fall in Southern California, the freeways get slippery because the water lifts the oil and grease that has collected on the pavement. The initial cloudburst also breaks loose tons of pollutants, sending them down the storm drains and into the ocean, according to Michael K. Stenstrom, professor of civil and environmental engineering at UCLA's Henry Samueli School of Engineering and Applied Science.

Stenstrom and his team are currently trying to ascertain how much higher the concentration of pollutants is in the first part of the storm-water runoff. If the data support his theory that the first burst of storm water contains the most potent concentration of toxins, Stenstrom said, "we have the opportunity for some natural treatment systems."

His goal is to find a way of reducing the amount of pollutants reaching the ocean. He hopes to use the data he is collecting "to save money because there is such a high volume of storm water that you can't possibly treat it all."

This is the fourth year of a $1.2 million research project, funded by Caltrans.

Mixed with the crankcase drippings and partially burned fuels that become polynuclear aeromatic hydrocarbons (PAHs), some of which are carcinogenic, the toxic stew that makes up storm-water runoff also contains heavy metals such as zinc, copper, nickel and chrome, Stenstrom said. Some of these are the products of automobile corrosion; some comes from brake pads.

"When a car hasn't been washed in a while, you can see a layer of black powder around the wheels. That powder is from the brake pads and can be loaded with heavy metals," Stenstrom said.

Stenstrom noted that some PAHs can be found in soot-like, micron-size particles. He cited diesel engines as one of the main sources of these particles.

Because conventional storm drains were designed to prevent flooding, they provide what Stenstrom calls "the biggest, slickest pipe to the ocean."

"If you want to prevent floods, that's the way to do it. Get the water down to the ocean," he said. "But when you push it down to the ocean that quickly, you transport all the contaminants along with it."

The cost of treating all the storm-water runoff is prohibitive. "One big rainstorm around here is like two months flow at the Hyperion Wastewater Treatment Plant," Stenstrom said. "We spent $3?4 billion dollars down there and you can't imagine how much it would cost to have a plant that would treat all the storm water."

Instead, Stenstrom said, "Let's try to take some of the water -- as much as we can -- and hold it up on the land, giving the pollutants a chance to be removed and maybe, just maybe, we'll be able to reclaim some of it, too."

To accomplish this, Stenstrom advocates constructing bioinfiltration basins along the freeway shoulders. These would consist of a trench about two feet wide and three or four feet deep. It would be filled with gravel and topsoil and covered with some type of grate that allows water to flow freely into the trench. Because the gravel is about 50 percent porous, each cubic yard of gravel can hold a cubic yard of water.

"When it starts to rain, the first really dirty water flows into the bioinfiltration basin, goes down into that gravel and topsoil and it stays there," Stenstrom said. "The rest flows off because the gravel is full."

This natural and cost-effective method would collect the first hour's worth of storm-water runoff. In addition to trapping the pollutants, Stenstrom said, this method could detoxify them, as well.

If allowed to filter into the soil, the top layer of soil will remove both heavy metals and PAHs, Stenstrom said.

"You can trap them there for many, many years and the PAHs will biodegrade over time," Stenstrom said. "There are organisms that will detoxify PAHs if you just keep them in the soil."

Such a method could treat the dirtiest water at the lowest possible cost, Stenstrom said. "We're trying to be clever and save our money and treat the most."

As the water seeps out, the gravel lets in air that promotes the growth of aerobic bacteria, creating an effective, natural treatment system.

Heavy metals are absorbed by the soil, where they remain trapped. The soil need not be replaced for at least 20 -- and possibly as long as 50 -- years, Stenstrom said.

Similar bioinfiltration basins are being used in other parts of the world including the East Coast of the United States and many Asian cities.

Stenstrom said he has become an advocate for the use of bioinfiltration basins to treat storm-water runoff. "I've been pushing this idea," he said. "A lot of what I'm trying to do is convince people in public office."


Story Source:

The above story is based on materials provided by University Of California - Los Angeles. Note: Materials may be edited for content and length.


Cite This Page:

University Of California - Los Angeles. "Natural Approach To Cleaning Up Toxic Freeway Runoff Urged." ScienceDaily. ScienceDaily, 3 April 2003. <www.sciencedaily.com/releases/2003/04/030403075010.htm>.
University Of California - Los Angeles. (2003, April 3). Natural Approach To Cleaning Up Toxic Freeway Runoff Urged. ScienceDaily. Retrieved September 20, 2014 from www.sciencedaily.com/releases/2003/04/030403075010.htm
University Of California - Los Angeles. "Natural Approach To Cleaning Up Toxic Freeway Runoff Urged." ScienceDaily. www.sciencedaily.com/releases/2003/04/030403075010.htm (accessed September 20, 2014).

Share This



More Earth & Climate News

Saturday, September 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: Wildfires in CA Burn Forest Asunder

Raw: Wildfires in CA Burn Forest Asunder

AP (Sep. 18, 2014) An out-of-control Northern California wildfire has nearly 2,800 people from their homes as it continues to grow, authorities said Thursday. Authorities said a man has been arrested on suspicion of arson for starting the fire on Saturday. (Sept. 18) Video provided by AP
Powered by NewsLook.com
Raw: Elephant Undergoes Surgery in Tbilisi Zoo

Raw: Elephant Undergoes Surgery in Tbilisi Zoo

AP (Sep. 18, 2014) Grand the elephant has successfully undergone surgery to remove a portion of infected tusk at Tbilisi Zoo in Georgia. British veterinary surgeons used an electric drill to extract the infected piece. (Sept. 18) Video provided by AP
Powered by NewsLook.com
Raw: Scientists Examine Colossal Squid

Raw: Scientists Examine Colossal Squid

AP (Sep. 16, 2014) Squid experts in New Zealand thawed and examined an unusual catch on Tuesday: a colossal squid. It was captured in Antarctica's remote Ross Sea in December last year and has been frozen for eight months. (Sept. 16) Video provided by AP
Powered by NewsLook.com
Man Floats for 31 Hours in Gulf Waters

Man Floats for 31 Hours in Gulf Waters

AP (Sep. 16, 2014) A Texas man is lucky to be alive after he and three others floated for more than a day in the Gulf of Mexico when their boat sank during a fishing trip. (Sept. 16) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins