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Systems Overview
NJ DEP Permeable Pavement Guidelines
Dispelling Permeable Pavement Myths
Pervious Concrete Porous AsphaltPermeable Interlocking
Concrete Pavement
Time Topic Speaker8:00 -
8:15Welcome/logistics Ted Green, PE, NJ LTAP Director
8:15 –
8:45
Overview of the seminar, New Jersey DEP
permeable pavement guideline +
dispelling permeable pavement myths
David R. Smith, Technical
Director, Interlocking Concrete
Pavement Institute (ICPI),
Chantilly, VA
8:45 –
9:30
Site selection and planning: design
considerations common to all permeable
pavements for stormwater water
management + site evaluation tool
Dave Hein, P. Eng. Vice
President – Transportation,
Applied Research Associates,
Inc., Toronto, Ontario
9:30 - 9:50 Break
9:50 –
10:45
Porous asphalt – design, specifications,
construction and maintenance
considerations + resources
Jim Purcell, PE, PMP, Technical
Director,
New Jersey Asphalt Pavement
Association, Trenton, NJ
Seminar Schedule
Time Topic Speaker
10:45 –
11:40
Pervious concrete – design,
specifications, construction and
maintenance considerations + resources
Ken Justice, PE, LEED AP,
Senior Director, Local Paving,
NRMCA, Ambler, PA
11:40 – 12:40 Lunch provided at the food court in the Student Center across the
parking lot
12:40 -
1:35
Permeable interlocking pavement -
design, specs, construction, maintenance
+ resources
David R. Smith, Technical
Director, ICPI, Chantilly, VA
1:35-
2:40
Municipal experiences with permeable
pavements
Robert Costa, PE, Costa
Engineering, Hackensack, NJ
2:40 – 3:00 Break
3:00 -
3:45
US EPA long-term monitoring of
permeable pavements in Edison, NJ
Mike Borst, US EPA, National
Risk Management Research
Laboratory, Urban Watershed
Management Branch, Edison, NJ
3:45 –
4:00Wrap-up David R. Smith & Ted Green
Primary Industry Information SourcesNational Ready Mix Concrete
Association & PCA (2004)ACI 522 & ASTM stds for infiltration,
abrasion resistance, in-place densityState ready mix concrete assocs State DOTs & stormwater manuals
National Asphalt Pavement Association & state assocs (2003)State DOT ATPB/OGFC specs
& stormwater manualsASTM material stds for mix, drawdownASCE standard underway
Interlocking Concrete Pavement Institute (2011)
State DOT & stormwater manualsASTM material stds, surface infiltration ASCE standard almost completed
Pervious Concrete
Porous Asphalt
Permeable InterlockingConcrete Pavement
Primary Industry Maintenance Information
National Ready Mix Concrete Association
National Asphalt Pavement Association
Interlocking Concrete Pavement Institute
See Chapter 52017: Tech Spec
technical bulletin
Research by Rob Roseen and James Houle, University ofNew Hampshire;Manoj Chopra, Central Florida University; University ofRhode Island
2014
Permeable Pavements ASCE Committee Report (260+ pages)
Fact sheets
Checklists – design, construction, mtce
Permeable pavement design information
Porous asphalt (PA)
Pervious concrete (PC)
Permeable interlocking
concrete pavement (PICP)
Grids
Maintenance
Standards, guide specifications & modeling methods
Research needs
ASCE e-book & print versionreleased April 2015
Source: VHB
Generally used when underlying soils are highly permeable
All captured water infiltrates into the soil beneath the pavement
Full-infiltration System Design
Used on low infiltration soils not allowing infiltration of captured water within 48 – 72 hours
Some water infiltrates into underlying soils
Underdrains drain excess filtered water
Partial-infiltration System Design
An impermeable liner (geomembrane) prevents infiltration into underlying soils
Filtered water exits the system via underdrain
Discharge (flow) control & water quality improvements
Little volume reduction
No-infiltration System Design
Volume & Pollutant Reductions• Volume reduction depends on soil infiltration rate &
storage volume in subbase – can be 100% in some cases
• Pollutant reductions (dozens of studies):
Sediment – TSS reductions 75% to 90%
Metals – High in clay soils - 50% to 90%
Nutrients – Higher in sandy/lower in clay soils; nitrification in partial infiltration designs after 24 hrs detention; nutrients handled w/ sand in subbase or w/ overflow bioswales
Oils – Digested by bacteria on aggregate surfaces
Permeable Pavement
Design
Structural
Analysis
Hydrological
Analysis
Traffic Load: ESALs,
Traffic Index
Subgrade Characteristics:
Mr, CBR, R-Value, K
Design Storm(s)Contributing Area
Runoff
Select the Limiting
(Thicker) Cross-
Section for Design
Determine Surface
& Base/Subbase
Thickness
Surface & Base/
Subbase
Properties
Structurally
Adequate?
Determine Depth of
Water & Base/
Subbase thickness
Infiltration Rate &
Volume Through
Subgrade
Outflow Rate &
Volume Through
Underdrains
Hydrologically
Adequate?No Yes Yes No
Revise Thickness
Revise Thickness or
Adjust Outflow
Time StepsVehicular UsePedestrian Use
AASHTO Typical ESALs by Road Class
Road Class Lifetime Design ESALs Arterial or Major StreetsUrban 7,500,000Rural 3,600,000
Major CollectorsUrban 2,800,000Rural 1,450,000
Minor CollectorsUrban 1,250,000Rural 550,000
Commercial/Multi-Family LocalsUrban 425,000Rural 275,000
Parking Lots < 275,000
Permeable Pavements
The Misuse of AASHTO H20 LoadsAASHTO H loading represents one load, not repetitions or ESALs
• Theoretical load for sizing members for bridge design by AASHTO
• Does not apply to pavement design
• Does not relate to ESALs other than one pass of an H20 load
Permeable pavements withstand H-20 & HS-20 loads
H-20 Load HS-20 Load
New Jersey StormwaterBest Management Practices ManualFebruary 2004 Chapter 9 . 7Standard for Pervious Paving Systems
Time for an upgrade
Permeable Pavement MythsDesign for 72-hour drawdown….Myth: Min. soil infiltration rate 0.5 in./hr required(from infiltration trench design specs)
Reality: 0.5 in./hr x 72 hours = 36 in. How about ≥ 0.017 in./hr x 72 hours = 1.25 in.Infiltrates NJDEP stormwater quality storm = 1.25 in.Conservative ~0.034 in./hr 2 x safety factor accounts for long-term subgrade clogging
Permeable Pavement MythsMyth: They clog & don’t infiltrate
Reality: No, if vacuumed regularly
Before After
Permeable Pavement MythsMyth: Sand bedding okay in PICP
Reality: NO! It easily clogs; bedding should be ASTM No. 8 stone; joints No. 8, 89 or 9 stone
From NJDEP Chapter 9.7 guidelines….
Myth: Don’t Compact the SoilCompaction required by designer:
Run lab Proctor density per ASTM D698 In-situ: compact & check density
Test infiltration per ASTM D3385Compaction = structural belt & suspendersDesign PICP for lower infiltration on compacted soilsDrain pipes may be required
Caltrans: compact to 88% to 90% relative density
Clay Soils Infiltrate…SlowlySome infiltration happens
Laboratory study by UC Davis, D. Jones, et al. for Caltrans
Per AASHTO T-215 constant head test
10-2 cm/sec = 14.2 in./hr
10-3 cm/sec = 1.4 in./hr
10-4 cm/sec = 0.13 in./hr
10-5 cm/sec = 0.014 in./hr
Reality: underlying soils – higher water content & latent heatAggregate void spaces: insulating properties of trapped airFaster thawing from meltwater
Surface infiltration rates high despite 28 in. frost penetration (Roseen 2011) Less plowing & encourage faster snow/ice melt (Roseen 2013; Cahill 2003)
Saturated subgrades drain prior to freezingExtended pollutant reduction seasonPotential winter maintenance cost savings & reduced liability
Myth: The Pavements Heave in Freeze & Thaw
Video source: J. Houle, UNHSC
Weighted Skid Resistance (BPN)
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Dense Mix Asphalt
Porous Asphalt
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Porous Asphalt
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Porous Asphalt
PA after spring rain on snow event
DMA after spring rain on snow event
21Slide source: J. Houle UNHSC
