BMP Monitoring Sites - Urban Drainage and Flood Control District

UDFCD BMP MONITORING SITES
Porous Asphalt Pavement
Geotextile Fabric
The geotextile fabric shall be installed below the sand
layer. The woven fabric shall conform to the following
requirements:
o ASTM D 4751 – AOS U.S. STD sieve #50 to #70
o ASTM D 4633 – Minimum trapezoidal tear strength
100 x 60 lbs
o Minimum COE specified open area of 4%
Possible geotextile fabric may be US 670, Mirafi
Filterweave 500, or approved equivalent.
Impermeable Liner
Fabric and Liner
Contained Cells
When expansive or NRCS Type D soils are present, or
potential for groundwater contamination exists, install a
16 mil impermeable
liner on the bottom and
sides of all areas to be
paved including the
bottom of the underdrain
trench. The impermeable
liner shall be wrapped to the top of the perimeter walls
and attached to the sides securely.
If soils are not expansive (NRCS Types A, B or C) use
woven geotextile fabric (as described above) as a liner.
Place fabric and liner by rolling parallel to the contours
starting at the most downstream part of the pavement.
Provide a minimum of 18” overlap between adjacent
sheets. Bring up geotextile fabric and impermeable liner
to the top of the perimeter walls and attach with roofing
tar or other adhesive or concrete anchors. Provide
sufficient slack in the geotextile fabric and impermeable
liner to prevent stretching during the installation of the
infiltration bed, choker course and wearing course
aggregate. Seal all joints of the impermeable liner to be
totally leak free.
Install lateral flow cut-off barriers using 16 mil or
thicker PE or PVC membrane liner or concrete walls
installed parallel to the contours (i.e. normal to the flow)
to prevent flow of water downstream and then surfacing
at the toe of the porous asphalt pavement installation.
Distance (L max ) between these cut-off barriers shall not
exceed: