design elements - San Jacinto Texas Historic District

Installation of permeable pavers.
Permeable paver parking lot.
Porous concrete.
IMAGE: CONSERVATION DESIGN FORUM IMAGE: CONSERVATION DESIGN FORUM IMAGE: CONSERVATION DESIGN FORUM
Maintenance Considerations
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Standard vacuum street sweeping
equipment and high pressure washing
may be used to maintain pavement
infi ltration capacity.
Porous asphalt and concrete paving may
have higher maintenance requirements
than permeable paving blocks.
Cost Considerations
Installation costs can be 1.5 - 2 times greater
than conventional concrete, but may require
less frequent replacement. The runoff
reduction capacity of permeable paving can
reduce the cost of stormwater engineering
and infrastructure (curbs, gutt ers, and storm
sewers.)
System Installed Cost/SquareFoot
Conventional Asphalt $1.00 - $2.50
Conventional Concrete $4.00 - $6.50
Porous Concrete $6.50 - $8.00
Gravel / Gravel-Grass $1.50 / $2.50 - $3.50
Porous Unit Pavers $7.00 to $12.00
Design Considerations
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Requires an open graded gravel base with
no fi nes.
Larger pore space improves eff ectiveness,
though larger openings may reduce the
strength of the paver for load bearing and
driving.
For vehicular applications, depth of base
and subbase materials should be at least
12” of coarse aggregate with no fi nes to
allow adequate drainage, prevent frost
heave, and provide adequate load bearing
strength.
Subgrade should be graded at minimum
1% slope to allow drainage.
Impermeable geotextiles should be used
between base and subgrade to prevent
infi ltration where contaminated subgrade
soils are present.
Underdrains should be placed at edge
of pavement to provide drainage as
necessary to prevent ponding in the base
for periods greater than 24 to 48 hours.
Permeable paving may not be appropriate
for land uses utilizing or storing hazardous
materials.
SAN JACINTO TEXAS HISTORIC DISTRICT CORRIDOR STANDARDS │ 141