Andrejs,
I think you now have the steepest driveway on the street!
The new parking lot down on Park Road off Cliff Street is paved with porous
asphalt and may be referenced in the Cornell University Dept. of Horticulture
report listed below.
Tom Shelley is right about the slope limit of 6%. If the surface is any
steeper water will tend to run over the pavement instaed of soaking down
through the pores.
The porosity of the subgrade and underlying soils also needs to be considered.
Generally parling lots have a sub-based of 8 inches to 12 inches or more of
crushed stone which can absord the rainwater coming through the porpuse asphalt
or concrete. Well-drained soils below the sub-base also help.
In this region there is a lot of concern over the long term ability of the
asphalt or concrete to remain porous, given the salt, sand and other stuff
dumped on our streets during the winter time. Of course in sub-freezing
weather and frozen ground pretty much shuts down the system during the winter
months.
Given the relative newness of the technology in this region contractor
experience with successful applications is also a big question mark.
There is a concept generically referred to as geogrid. Pre-fabricated from
either plastic or concrete, a geogrid consists of a series of 3 inch by 3 inch
openings created by a structural framework that supports the weight of a
vehicle. The geograid is placed in possition and the openings are filled with
soil and seeded to grass.
These systems work well as temporary parking lots or for emergency vehicle
access roads across lawns where you do not want to see a roadway. I don't know
how steep you can go with them, however. A big question mark too is the
survivabilty of the grass in what would be a high-salt environment.
What about going with conventional asphalt, but with some sort of bioswale
detention system at the bottom of the driveway or in another low spot on your
property. These "water gardens" are beginning to be used around this region in
order to meet new DEC regulations that mandate at least some
primitive treatment of stormwater runoff. They rely on a combination of
infiltration and plants to filter out runoff pollutants before the storm water
is discharged.
Could you direct the runoff from the driveway into something like that?
Good luck!
George Frantz
--- On Sun, 8/10/08, Thomas Shelley <[EMAIL PROTECTED]> wrote:
At 02:31 PM 8/9/2008 -0400, Andrejs Ozalins wrote:
>Does anyone have advice about permeable paving methods and/or local
>contractors who would know about and use such methods in driveway
>projects?
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