By ALEKSANDRA ROBINSON Capital News Service
By ALEKSANDRA ROBINSON Capital News Service
Published
11/21/09
The parking lots of Queen Anne's County's Bloomfield Farm will soon be modeling the latest in a series of efforts by the county to battle stormwater runoff pollution in the Chesapeake Bay.
Pamela Wood - The Capital
TOP: Pervious concrete, which allows water to soak into the ground instead of running off into the Chesapeake Bay, is used on a pathway at the Smithsonian Environmental Research Center in Edgewater. Queen Anne’s County’s Bloomfield Farm is getting a similar treatment. Urban and suburban stormwater is the only growing source of pollution to the Chesapeake Bay, and pervious or porous pavement is one way to combat the problem.
BOTTOM: Where most concrete has fine particles to fill gaps between larger pieces, permeable concrete has none, allowing water to pass through.
Pervious concrete - the technology Queen Anne's County will use in Bloomfield Farm's parking lots - allows water to drain straight through into a reservoir below the pavement where it can subsequently soak into the ground. Most concrete and asphalt don't allow rainwater to penetrate the ground, instead the water runs off and pollutes waterways.
Urban and suburban runoff is one of the top contributors to the Chesapeake...
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More infomation - 2009-11-23 17:19:23
I've been around the product quite a bit. I've see more grass grow on my asphalt driveway than any of the pervious concrete parking areas I've seen. If anything, there would be less growth because there is less surface area for a plant to take root. Vacuuming isnt nearly as effective as a power wash from what Ive seen, so no need for RoundUp. You can go years between cleanings, but it really depends on what is happening on that piece of property.
In regards to freezing, there have been a lot of advances in engineering, mixing and placing pervious concrete over the past few years. First, the drainage should be designed so the concrete does not hold the water, and second, the void ratio of pervious concrete is about 20% while water only expands 9%. There are hundreds of projects in far colder climates that Maryland and several in Maryland over the past 7 or 8 years.
Pervious concrete also helps out with the urban heat island effect as does traditional concrete. The brighter pavements reflects the heat and light which lowers the electric bill.
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Steven Tripp - Waldorf, MD - Karma: Neutral
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Other issues - 2009-11-21 11:29:36
I would have liked to have heard discussion of how one deals with plants growing from this material. I could see many homeowners offsetting the potential benefits of this type of material by using tons of Roundup or other herbicides on their driveway.
Also, and I'm sure this relates to the vacuuming, I wonder how quickly these materials might become none porous due to sediment filling in the spaces in the top layer or even down into the material.
I like the idea a lot and think it's a hugely important concern and potentially a great approach to remediating one of the problems that paving creates. I'd also like to hear any ideas that address the heat island effect of pavements.
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Mark McCabe - Eldersburg, MD - Karma: Neutral
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Missing Critical Info - 2009-11-21 08:04:15
Too bad the reporter failed to talk about some of the reasons permeable concrete is typically not used around here. Most importantly, in the past, permeable concrete has not been used in climates where there is a risk of below freezing temperatures. If there are wet conditions on the permeable concrete and the water freezes then the permeable concrete gets broken up. I would be interested to know if someone has come up with a solution to this problem.
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Spencer Leech - Annapolis, MD - Karma: Neutral
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