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Storm Water, Development Bad Mix

Increasing development and no control over storm water means more flooding.

This is the first in an occasional series addressing storm water issues.

There is nothing quite like the sound of a rainstorm during a summer evening.

To some people, it is a relaxing sound that helps them drift off to sleep.

To others, it is a reminder that there will be a big mess in the morning, as water struggles to find a clear path to run downhill, over driveways, around houses, down sidewalks and across backyards.

During the more than 12 hours of rain received in McLean on Friday, May 20, the McLean Volunteer Fire Department received more than a dozen calls for residential flooding. During the same time, Dominion Electric had trucks scattered throughout the county to address power outages caused by fallen trees. The culprit, a growing concern in the county, was storm water flooding.

According to the Department of Public Works and Environmental Services, storm water runoff is the name given to water, either from rainfall or melting snow, that accumulates on the ground, saturating the ground water table to capacity, and pools on the surface.

"In the 1960s when the county experienced a dramatic growth spurt, the county didn't have any requirements to mitigate storm water runoff," said Sally Ormsby, elected director of the Northern Virginia Soil and Water Conservation District. "As we've continued to develop and increased the impervious surface, the runoff is not being absorbed into soil."

The result, she said, is surface pooling, where water collects in a low point in a backyard or street. Additionally, water will always run downhill, she said, and the more water that has accumulated, the faster it tries to find a way downhill to an awaiting stream bed.

"Our streams have to accommodate not only an increase in the amount of water, but also the velocity with which it flows into the stream," she said.

AS A RESULT, she said, "most streams in the county have been deteriorated through stream bed and stream bank erosion," in which the soil around and below a stream is literally washed away, contributing further to water pollution and making the ground in those areas unstable.

There are several contributing factors to the effects of storm water, Ormsby said.

"The increase of impervious surfaces prevents our ground water supply from being replenished," she said.

When the ground is covered by hard surfaces that do not permit water to be absorbed, be it pavement, sidewalk, brick, stone, houses or other construction, it is considered impervious, she said.

Up to 17 percent of the county is covered by impervious surface, according to the Storm water Management Division of the Department of Public Works and Environmental Services.

"As the county is nearing build-out, we will find people developing homes in land that they avoided before," she said. Several areas throughout the county which have clay as opposed to topsoil, traditionally believed to be an unstable surface for construction because of its tendency to shift, are becoming viable locations to build homes, she said.

An increase in housing in any neighborhood creates impervious surfaces, she said, and takes away from what may have been a natural downhill path for the water to follow.

"If neighbors do not properly care about what happens to their own runoff, it can cause flooding in their community," Ormsby said.

Flooding and runoff have played a major role in the pollution of the county's 980 miles of streams and other bodies of water. Throughout the county's 30 watershed areas, all of which eventually lead to the Chesapeake Bay and then the Atlantic Ocean, every mile of polluted water is like a cancer, spreading out and infecting a larger body.

"The county is under permit to maintain the water quality in our streams," said Scott St. Clair, director of the county's maintenance and storm water management branch of the Department of Public Works and Environmental Services. "We're required to inspect all storm drain systems once every five years and make sure all the pipes and channels are open and flowing."

SHOULD A PROBLEM come up during that five-year period, a team from St. Clair's department will be assigned to inspect the site and clean up any debris that may be clogging a residential pipeline or drainage ditch, or take other measures to improve the flow of water away from a home, he said.

"People think all the water is supposed to go into the pipe system, but not all the water can," he said. The drainage pipes collect water and transport it to an underground sewer system or lead directly to a river, and once either of those is filled, the water does not have a place to go, causing it to pool.

"Better subdivision standards went into effect in the 1960s, and my guess is that 60 percent of the county has been developed under those new standards," St. Clair said, but there are still "pockets where water will collect quickly and the pipes become stopped up and cause house and road flooding."

To address the storm water issue, Fairfax County is dedicating one penny of the tax rate for fiscal year 2005 for a special storm water maintenance project, expected to bring in a total of $17.9 million, said Dranesville District Supervisor Joan DuBois.

"When the original Comprehensive Plan was written, no one contemplated the amount of build out we'd have or what it would look like," DuBois said.

The development that has occurred has created problems the county could not have foreseen, she said, so the current government is taking strides to deal with the situation.

"We know there are things we have to do" to help alleviate the flooding and storm water problems, she said, adding that there are "four or five projects" that are currently awaiting approval before the county can begin implementing them.

"Part of the problem is we haven't received adequate funding to address the storm water problem yet," she said, but the money received by the county during the current tax year should help.

"It's going to take county measures, but it's also going to take an awareness in the community" to find solutions that will work, she said.

HOWEVER, THE only part of the problem that cannot be fixed is the obvious one: rain will not stop falling.

"We went through a long drought for several years, and a few years ago we got into a weather pattern where our water table is just about saturated," DuBois said. "Because of that pattern, our water table is higher, I think, and people who weren't originally living in a flood plain now find their basements flooding when we get a lot of rain."

To better determine where the flood plains and watershed of the county lie and how many residents are directly affected by them, the county is in the middle of a watershed planning project.

"We want to find out how healthy our watersheds are," she said. "We need to find out what we can do to make them healthy and help people understand what a watershed is and why it's important."

Unfortunately, the storm water problem is much bigger than just development, covered ground and damp basements.

"The only people who really understand what storm water is and why it's a problem are engineers and the people at the end of the stream who have flooded basements," DuBois said. "You don't understand it until you become involved with it directly."