Sustainable Stormwater Management in Road Environments: Porous Asphalt for Local Roads Robert Roseen, PE, D.WRE, PhD, Thomas Ballestero, PE, PhD, PH, CGWP, PG, James Houle, CPSWQ, Alison Watts, PhD, Tim Puls The UNH Stormwater Center Environmental Research Group, Department of Civil Engineering University of New Hampshire Ohio Transportation Engineering Conference Columbus, OH 10/19-10/20/2010
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Sustainable Stormwater Management in
Road Environments:
Porous Asphalt for Local Roads
Robert Roseen, PE, D.WRE, PhD, Thomas Ballestero, PE, PhD, PH, CGWP, PG,
James Houle, CPSWQ, Alison Watts, PhD, Tim Puls
The UNH Stormwater Center
Environmental Research Group, Department of Civil Engineering
University of New Hampshire
Ohio Transportation Engineering Conference
Columbus, OH
10/19-10/20/2010
Dedicated to the protection of water resources through effective stormwater management
• Research and development of stormwater treatment systems
• To provide resources to stormwater communities currently involved in design and implementation of Phase II requirements
Gregg Hall ● 35 Colovos Road ● Durham, New Hampshire 03824-3534
603.862.4024 ● http://www.unhsc.unh.edu
Introduction - Objective
We can do better at stormwater
management in roadways and
road corridors
Case Study –
Porous Asphalt Road
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Boulder Hills, Pelham, NH
2009 Installation of 900’ of first PA private
residential road in Northeast
Site is nearly Zero discharge
LID subdivision 55+ Active Adult Community
Large sand deposit
Conventional Site
Design
LID Design
The Scope
Built on 9% grade
14 acres of previously undeveloped land
5 multi-family buildings, a community well,
and a private septic system
All driveways and sidewalks in the
development are porous asphalt
Fire lanes consisting of crushed stone that
also serve as infiltration systems for rooftop
runoff. 7
The Design
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Gravel Filter Layer over 3/8-in stone base
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Cutoff for Stone Layer Flow
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Choker Course ¾-in Stone
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Choker Course Compaction
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Infiltration
Testing of
Gravel
Layer
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THE FINISHED PRODUCT
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2009 Porous Asphalt Paving Costs
DMA $100/ton,
PA $125/ton placed by machine for
parking and residential road and
driveways
Complicated jobs with handwork are more
expensive $170/ton
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Cost Avoidance
Avoided use of 1616’ of curbing, 785’
pipe, 8 catch-basins, 2 detention basins, 2
outlet control structures
1.3 acres less of land clearing
Conventional SWM=$789,500 vs LID
SWM=$740,300, $49,000 savings (6.2%)
Comparison of Unit Costs
6% savings on total cost of SW infrastructure for a ~zero discharge site
But There is More….
Salted twice, then never again (less salt to
receiving stream)
Better traction than standard DMA
Fire fighting storage from rooftop capture
No concern about mosquitoes in the ponds
Very little site runoff (pollutant load to
stream very small, no thermal pollution)
Receiving stream in geomorphic equilibrium
not taxed 23
State of the Practice with Porous
Pavements
Significant advancements in porous asphalt
strength, durability, and production costs have
been achieved
Large increase in significant PA installs for
light duty, residential, commercial, and state
road applications
However, a large number of installations STILL
continue to be sub-standard
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Common Pitfalls Inappropriate porous asphalt mix selection with
respect to durability leads to raveling and low
durability
Poor subbase compaction—tendency to under-
compact due to concerns regarding infiltration (leads
to rutting)
Poor asphalt compaction—tendency to under-
compact due to weaker subbase (leads to low
pavement durability)
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All issues can be addressed through
qualified engineering oversight
MODERATE
DURABILITY: Pre-
Blended PG 64-28*
SBR with 5 pounds of
fibers per ton of
asphalt mix. This mix
is recommended for
large projects > 1
acre where high
durability pavements
are needed.
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*or PG binder typical to
region; **PG binder 2
grades stiffer
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Sieve Size (inch/mm) Percent Passing (%)
0.75/19 100
0.50/12.5 85-100
0.375/9.5 55-75
No.4/4.75 10-25
No.8/2.36 5-10
No.200/0.075 (#200) 2-4
Binder Content (AASHTO T164) 6 - 6.5%
Fiber Content by Total Mixture Mass 0.3% cellulose or
0.4% mineral
Rubber Solids (SBR) Content by Weight of the
Bitumen 1.5-3% or TBD
Air Void Content
(ASTM D6752/AASHTO T275)
16.0-22.0%
Draindown (ASTM D6390)* < 0.3 %
Retained Tensile Strength (AASHTO 283)** > 80 %
Cantabro abrasion test on unaged samples
(ASTM D7064-04)
< 20%
Cantabro abrasion test on 7 day aged samples < 30%