Jul 10, 2012 6:08 PM by Andy Koen
Large wildfires like the Waldo Canyon Fire not only consume trees and plants, they also change the landscape right down to the dirt.
Brad Rust, a soil scientist for the US Forest Service Burn Area Emergency Response team, says burning leaves and pine needles of can cause increased runoff.
"It has oil waxes in it and when it burns those fuels and vapors are pushed down into the soil," Rust explained.
Once enough oil builds up, it creates a water repellant layer in the dirt. In heavy rain, that oil layer causes the top soil to break apart more easily.
That easy erosion can clog drainage ditches and culverts with loose soil and potentially washout roads. Dana Butler, a hydrologist with the US Forest Service, says clogged culverts have already lead to street flooding along US Highway 24.
"Likely what we're seeing coming onto the highway is as a result of some of these culverts failing, getting clogged and then water coming onto people's driveways and moving down towards Highway 24 and though the neighborhoods," Butler said.
The forest service will use Rust's measurements to pinpoint problem areas and work with the Colorado Department of Transportation and other local road crews to keep the road drains clean. It can take 2-3 years before the oils in the dirt dissipate, diminishing the risk of mudslides.
Meanwhile, another agency called the Natural Resources Conservation Service will help individual property owners to steer erosion away from their homes. Help may include digging trenches or building berms to keep the water away.
The conservation teams will contact those homeowners who are most at risk for emergency protection. However, all property owners in the burn area are encouraged to learn more about the program by visiting www.co.nrcs.usda.gov.
Money to pay for emergency mitigation work will come from a combination of federal and local funds.