BMP Monitoring Sites - Urban Drainage and Flood Control District
BMP Monitoring Sites - Urban Drainage and Flood Control District
BMP Monitoring Sites - Urban Drainage and Flood Control District
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UDFCD <strong>BMP</strong> MONITORING SITES<br />
Porous Asphalt Pavement<br />
POROUS ASPHALT PAVEMENT<br />
Description Location Typical Details Installation<br />
Photo Gallery <strong>Monitoring</strong> Data Other Examples<br />
Description<br />
General<br />
Porous asphalt pavement may be substituted for conventional<br />
pavement on parking areas <strong>and</strong> areas of light traffic provided the appropriate<br />
grades, subsoil, drainage characteristics <strong>and</strong> groundwater conditions are all<br />
suitable. Porous asphalt consists of an open graded hot mix asphalt that contains<br />
less than 3% of fines passing a #200 U.S. St<strong>and</strong>ard Sieve. The absence of<br />
fines creates permeability. The infiltration bed below the asphalt is<br />
comprised of choker course<br />
aggregate, course aggregate<br />
<strong>and</strong> a s<strong>and</strong> bed. As with any<br />
asphalt pavement installed<br />
in Colorado, the freeze/thaw<br />
cycles <strong>and</strong> the<br />
expansive soils must<br />
be taken into account. It is<br />
recommended that porous asphalt be placed between April <strong>and</strong> October<br />
(when the ambient air temperature is 55 degrees Fahrenheit or greater) with<br />
sufficient base course aggregate, an underdrain trench <strong>and</strong> an impermeable liner<br />
to prevent failure. Proper site evaluation shall take place prior to approval of a<br />
site for porous asphalt application <strong>and</strong> shall include tests for soil permeability,<br />
porosity, depth of seasonal high water table, <strong>and</strong> depth to bedrock. Slopes<br />
should be flat or very gentle <strong>and</strong> shall not exceed 5 percent.<br />
Site Specific<br />
The porous asphalt pavement site monitored by the<br />
<strong>District</strong> is located at the Denver Wastewater Management<br />
Division building. The asphalt was placed in April of 2005 by<br />
companies who donated time <strong>and</strong> materials under the leadership<br />
of the Colorado Asphalt Pavement Association. The design<br />
included 3” of open graded hot mix asphalt <strong>and</strong> 18.5” of #67
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