Most parking lots may resemble a man-made wasteland even with cars sitting on top of them. But now they can serve a dual purpose by helping filter out pollutants in rainwater that might reach underground water sources.
The Environmental Protection Agency kicked off a study this week on how pavement materials can improve water filtration. A 43,000-square-foot section of a parking lot at the agency's Edison, New Jersey facility serves as the test bed for three different types of permeable pavement. The agency also planted several rain gardens this summer to see how vegetation can aid in water filtration.
Storm water runoff can gather large amounts of debris, chemicals (antifreeze, motor oil) and other nasty sediment as it flows across impermeable parking lot and rooftop surfaces. Porous pavement could go a long way toward countering that--EPA employees will even contribute to the experiment during their daily commutes by representing traffic and adding vehicle-related pollution like leaking oil.
The filtered water won't all go into the soil. Certain sections of the porous pavement test beds are lined with geotextile fabric to collect water samples. The impermeable fabric sections also have a perforated pipe to drain accumulated runoff into a dedicated collection tank.
So next time you're watching dirty storm water run along gray pavement, just remember--the EPA's Green Infrastructure Research Program has got your back.
Question? If this is a filter, what happens when the filter becomes full? Seems like you would back to step one again. But dont get me wrong this is a great step towards cleaning up storm water.
Good question. I am thinking because the pores become full, because it can't "accept" anymore dirt, the excess dirt will remain on the top of the "cement" and then run off. But hopefully you don't just have one cement block but an array of them, so the top layer of dirt that couldn't be accepted would keep trickling over other cement blocks until it reaches one that isn't full. Maybe at the edges of these large cement block arrays they could have runoff pipes that possibly lead to a waste container or something.
First thing I thought of was how are they going to keep the concrete from blowing to pieces when it repeatedly freezes & thaws in winter?
I agree. There is no way to backflush the filter. Once filled, it is done. Freezing would also shatter it, turning it back into the real permiable parking surface - gravel.
Gravel lets water through, and when it sinks or clogs, is easily refreshed with more gravel.
But why fix what isn't broken? Catch pools are effective, efficient, and all natural ways to filter excess run off. They provide habitate for amphibians, fish, turtles, and other swamp-loving life. They filter the water exceptionally well. They for development to be broken up. They prevent flooding and help retore aquifers injured by paving. With a little balance, they are not even the mosquito pits that people think they are.
The biggest problem with this filtration system is that grass will grow on top of the pavement.
The alternative to kill grass with herbacides or salt is more dangerous than the minimal runoff that happens.
One alternative I saw used in Kansas is to put concrete blocks down with the holes facing up. Fill with dirt. Mother nature will fill with grass. All you need to do is to mow the area when you mow your grass.
Problem? it is a bit difficult to remove ice from this system. Snow not so bad but ice is a problem. The good part is that ice will not build up so bad as it does not pavement.
Do we need a research project to tell us all this?
I have actually poured this crazy stuff, actually you just tamp it down because it's the consistancy of rice crispy square mix. The manufacturers claim it can withstand the freeze/thaw cycle(remains to be seen). I've been a cement mason in NW Ohio for 16 years and I doubt it will last more than a handful of seasons. The way it works, and it's a pain, you have to first put down a vapor barrier,then stone, then you place concrete, still sloped to a drain. The whole reason for this is to not have standing rain with all the contaminants on the surface that may not necesarrily go to a drain. This stuff is very expensive so very few builders would bother.
More wasted government cash wasted, Im pretty sure any "normal" person could have taken this concrete at face value
But people here on popsci arn't "normal"
The is a great invention ,but where are you going to put waste
on the ground.Hopefully not in landfills.
Thats pretty awesome I must admit!! Surely there will be waste resulting from this though?
Good invention but like manys another needs to be developed further, in an effort to overcome obvious drawbacks, cost etc