Horizontal/Subsurface Infrastructure & Transportation

A number of consultants and academic researchers who have been developing solutions to technical questions regarding the use of permeable pavement are wondering why they are not being used more often.  The reasons we hear about from cities are a.  too expensive, b. too risky, c. can't be maintained, d. the current regulations and specifications still require me to put in a conventional stormwater system which makes permeable pavements too expensive.  It seems to us that most of the technical questions have been answered in the past 10 years, everyone is updating their design guides, and ASCE is putting out guidance.  Is the slow implementation because of lack of information?  Risk-averse, no-reward for innovation decision-making environment?  Or are there still technical gaps that need to be solved and if so what are they?

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John Harvey P.E., M.ASCE
Professor
University Of California
Davis CA
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As Chair of the ASCE T&DI Permeable Interlocking Concrete Pavement Committee we are in the final stages of publishing a Standard Guideline on the design, construction and maintenance of PICP.  The draft standard should be going out for public comment in the next couple of months.  The standard is the culmination of over 4 years of work by both water resource and pavement engineers to provide guidance to planners, designers and owners of permeable pavements.  While the design of permeable pavements has developed well, one of the barriers that I see is the lack of education of constructors and owners in the proper construction and maintenance of permeable pavements.  Permeable pavement construction requires greater detail to subgrade preparation, drainage and materials choices.  All pavements require maintenance, however, few receive that maintenance in a timely and effective manner.  Part of the problem, I believe, is education.  Mix design, placement, consolidation and curing of porous asphalt and pervious concrete is critical to its long term performance.  I have been on construction sites where everyone knew there were permeable pavements yet landscapers dumped their topsoil on the permeable pavement and used Bobcats to push it around on the pavement to finish the landscaping.  If you are interested in seeing the "good" the "bad" and the "ugly" for permeable pavements, look for the ASCE and Forester University Webinars on the subject.  See photo.  Permeable pavers are under the topsoil on this construction site.

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David Hein P.E., P.Eng, M.ASCE
Prinicpal Engineer,
Applied Research Associates, Incl.
Toronto ON
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How would I be able to get a copy of the draft standard when it becomes available?

 

Alan Sirkin, P.E., G.C.

Fellow & Life Member, ASCE
Sirkin Enterprises
3500 N. Bay Homes Dr.

Miami, FL 33133
305-665-3349 office  Miami
305-989-7447 cell
alan@...

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Alan Sirkin P.E., F.ASCE
President
Miami FL
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Original Message:
Sent: 05-17-2017 07:36
From: David Hein
Subject: Permeable Pavement

As Chair of the ASCE T&DI Permeable Interlocking Concrete Pavement Committee we are in the final stages of publishing a Standard Guideline on the design, construction and maintenance of PICP.  The draft standard should be going out for public comment in the next couple of months.  The standard is the culmination of over 4 years of work by both water resource and pavement engineers to provide guidance to planners, designers and owners of permeable pavements.  While the design of permeable pavements has developed well, one of the barriers that I see is the lack of education of constructors and owners in the proper construction and maintenance of permeable pavements.  Permeable pavement construction requires greater detail to subgrade preparation, drainage and materials choices.  All pavements require maintenance, however, few receive that maintenance in a timely and effective manner.  Part of the problem, I believe, is education.  Mix design, placement, consolidation and curing of porous asphalt and pervious concrete is critical to its long term performance.  I have been on construction sites where everyone knew there were permeable pavements yet landscapers dumped their topsoil on the permeable pavement and used Bobcats to push it around on the pavement to finish the landscaping.  If you are interested in seeing the "good" the "bad" and the "ugly" for permeable pavements, look for the ASCE and Forester University Webinars on the subject.  See photo.  Permeable pavers are under the topsoil on this construction site.

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David Hein P.E., P.Eng, M.ASCE
Prinicpal Engineer,
Applied Research Associates, Incl.
Toronto ON
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When available you'll be ale to obtain a copy of the permeable pavement standard through the ASCE Library (www.ascelibrary.org)

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Jonathan Esslinger P.E., F.ASCE, CAE
Director, Codes & Standards and Technical Advancement
ASCE
Reston, VA
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Original Message:
Sent: 05-24-2017 11:01
From: Alan Sirkin
Subject: Permeable Pavement

How would I be able to get a copy of the draft standard when it becomes available?

 

Alan Sirkin, P.E., G.C.

Fellow & Life Member, ASCE
Sirkin Enterprises
3500 N. Bay Homes Dr.

Miami, FL 33133
305-665-3349 office  Miami
305-989-7447 cell
alan@...

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Alan Sirkin P.E., F.ASCE
President
Miami FL
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I worked on a project where permeable pavement allowed a commercial development to happen on a parcel of land that only lacked access to city drainage, but otherwise was prime property for the commercial use.  It was an innovative last resort that allowed a good project that had widespread support to move forward.  Had the jurisdiction not accepted permeable pavement there'd have been no project at this prime interesection for years.

My involvement ended after the project was entitled.  I have long meant to go back to see how the pavement has been maintained and how it is holding up over time.  It was installed 7-8 years ago.

It seems like great technology and something we should be doing more of, especially in light of our need to do more to recharge groundwater supplies in California and to mitigate runoff in high water years when we face increased flood risk.

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Clint Rehermann P.E.
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In my experience, contractors and agencies (specially non-DOT agencies) know very little about permeable pavements and open-graded friction courses.  Even if they have a few miles installed, they know very little on how to maintain it.  I believe education and information dissemination is what is missing.  If agencies know that they have options, including permeable pavements, they will start demanding it and contractors and engineers will respond to this request.  On the other side, if agencies do not know enough about permeable pavements and are not going to perform the right type of maintenance on it, maybe it is better for them not to install it in the first place.

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Nathan Kebede P.E., M.ASCE
Pavement Engineer
Chicago IL
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With respect to pervious concrete pavement (PCP), there are three factors that impact its long term performance: adequate structural capacity of the pavement system, sufficient drainabilty to negate the use of storm water inlets, and long-term, regularly scheduled maintenance to assure its drainabilty. Design and construction guides need to address these factors. Edge confinement and stiff drainable base add to its structural support and drainabilty. It is important to engineer a PCP mix design for the specific application, using proper cement content, and aggregate size and gradation to achieve proper strength and drainage properties. The key in construction is proper placement and compaction to provide the pavement with the necessary strength without compromising drainability. Surface ravelling and clogging of the voids from dust and debris shorten the service life of PCP. Developing performance tests to assure the structural support and drainability will provide the necessary assurance to the facility owner. Unless owners are assured of PCP performance, they will continue to require a back up drainage system. Every design and construction contract has to include a statement that the owner should perform  quarterly maintenance of the pavement including washing and vacuuming the surface. I also suggest that designers and contractors visit their projects and learn form good and poor performing PCPs.

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Jamshid Armaghani Ph.D., P.E., M.ASCE
Vice President
Global Sustainable Solutions
Gainesville FL
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The issue for most cities is that it is too costly to maintained properly.  So after very little time the "permeability" is gone.

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Stephen Palen, P.E.,CESSWI, MASCE
Director of Public Works
City of Wood River
Wood River, IL
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Our area has a large amount of expansive clay.  We go to great lengths to keep water out of the subgrade.  Water in the subgrade has a very negative effect on the load bearing capacity of the pavement.  We have encouraged permeable pavement in parking lots that park primarily cars.  More substantial pavement is required for truck lanes and fire vehicle access routes.  In heavily traveled routes I would expect pumping and subsequent loss of material in the subgrade.  We have experimented with permeable surface courses in order to achieve better skid resistance but found them difficult to apply and maintain.  Raveling was common in the mix designs we used.

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James Anderson P.E., M.ASCE
Principal, Anderson Consulting
North Richland Hills TX
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Permeable pavements aren't designed and allowed in Virginia when the underlying soils has an infiltration rate less than 0.5 inch/hr: DEQ Virginia, etc. The plastic and mostly expansive soils of Virginia have in-situ infiltration rates much less than 0.5 "/hr, hence porous pavements shouldn't and won't be built on such soils here.

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Umakanthan Sivapalarasah P.E., M.ASCE
Fairfax County Department of Public Works
Fairfax VA
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Original Message:
Sent: 05-17-2017 22:27
From: James Anderson
Subject: Permeable Pavement

Our area has a large amount of expansive clay.  We go to great lengths to keep water out of the subgrade.  Water in the subgrade has a very negative effect on the load bearing capacity of the pavement.  We have encouraged permeable pavement in parking lots that park primarily cars.  More substantial pavement is required for truck lanes and fire vehicle access routes.  In heavily traveled routes I would expect pumping and subsequent loss of material in the subgrade.  We have experimented with permeable surface courses in order to achieve better skid resistance but found them difficult to apply and maintain.  Raveling was common in the mix designs we used.

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James Anderson P.E., M.ASCE
Principal, Anderson Consulting
North Richland Hills TX
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Permeable Pavements and Open Grade Asphalt have been in used for over 40 years. The design requirements of the two have little in common other than the use of Asphalt as a binder. The structural carrying capacity, and test procedure to determent the proper amount of asphalt are different. Their acceptability varies through out the country. I design open grade asphalt and development my own method of determining the optimum asphalt content. It was used on airports and roads for skid resistance. The type, configuration, and gradation of the aggregate will vary with the problem you  are solving with the project. 

Permeable pavement has no business being considered in area of expansive soil, unless you have protected the subgrade from the flooding of the water. in the North, you are asking for terrible freeze than problems and subgrade failure during the thaw. In the south, coastal areas would work great. I have used it in the bottom of detention ponds that were parking lots, achieving two objectives. (sand and gravel base)

I worked with MO. DOT years ago and reduced accidents by 80% and a curving area of I-70 in Kansas City. By placing a open graded surface coarse over the existing concrete pavement. 



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Robert Hinton P.E., M.ASCE
Consultant
Tulsa OK
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Permeable pavements have limited use in our part of Iowa. The urban/infill areas are the only places in which they make financial sense. Many of these sites utilize the Contech " Stormtech" under-pavement storage systems. I think this may have more to do with the marketing efforts. Permeable pavements are not marketed aggressively. The utilization of the systems reflects this.  There is a high level of skepticism from our local engineers but some are trying them.
We have installed a number of porous asphalt systems in the Cedar Rapids/Iowa City area over the years. Many of these pavements are beneath other features; horse barns for liquid waste removal, athletic surfaces or airport pavements. We have also experienced the frustration of others using these pavements as staging areas when they've been installed as parking lot surfaces. We have one installation with great owner "Buy-in"! The property manager is very diligent about keeping the pavement clean and functioning. He has experimented with power washers to determine the optimum angle to remove any sediment from the pavement. Not all owners are this proactive!

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Dewayne Heintz A.M.ASCE
Project Manager
L.L. Pelling Company
North Liberty IA
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