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When rain hits pavement, it rushes along the ground, picking up
pollutants on the way, and flows into the nearest body of water.
According to Tim Cahill, an environmental engineer from West Chester,
parking lots and rooftops make it hard to recharge groundwater supplies
near cities.
We only get rainfall impacted streamflow about 30 days a year.
And so 11 months of the year, all the water coming down our natural
streams is coming out of storage. And so if we don't have that water
getting recharged, into those aquifers, the streams will literally
dry up.
Cahill says porous pavement which lets rain seep slowly into the
ground is a cost-efficient way to deal with stormwater runoff...
without building rain retention basins next to every large parking
lot.
Porous pavement is only a 2 inch thick layer of asphalt that drains
like a sieve and looks like normal asphalt. But underneath it is
a bed of stone. The bed of stone can be a foot and a half to two
foot thick. And then the water that drains through the pavement
is held in that stone reservoir and then infiltrates slowly into
the undergrowing soil. Cahill says the asphalt runs about the same price as regular paving materials. While the stone bed can be an additional cost, he says it's comparable to the costs of concrete pipes traditionally used to control stormwater.
More information's available on the web at GreenWorks.tv. I'm Brad
Linder.
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