Permeable Pavements

[Granite]

Is anyone out there involved in permeable pavements? I'm interested in comments from all sides: paver mfr, contractor, engineer, architect, etc. What systems have you used? What were the results? How did the project develop? Although permeable paving seems to be a hot topic these days, I've heard of very few actual installations. What's it going to take for permeable paver systems to actually catch on and be recognized as a legitimate alternative to solid surfaces? Everywhere I go, all I see are asphalt parking lots; yet all I ever hear about are the problems created by these surfaces: excess rainwater runoff overwhelming storm systems. Please post any and all comments. Thanks

[Whyzman]

I live in the Twin Cities (Minneapolis/St. Paul) area in Minnesota. Our climate lends itself well to using permeable pavement applications. I see paver installs on nearly all new homes I work on that exceed 1 million dollars. Homes in the million on up range usually also dedicate a substantial chunk of money to overall landscaping. Anything less that that, and I suspect cost is the determining factor.

It would be interesting to look at a cost comparison for any given driveway between asphalt, concrete, and pavers...say, using standard holland pavers.

[Glenn W]

Permeable paver installations seem to run hot and cold. Sometimes there seems to be a lot of active projects and other times it seems the market is dead. Certain regions also have more activity than others. ICPI just printed a brief article about a recent project in Vancouver, BC. We need more of this type of good publicity to reach engineers, city planners, developers, etc. Each project completed, if installed properly, will help advance permeable paver systems. At the same time, each project not properly installed will set things back and could ruin this segment of the industry. Education is the key – and not just educating those outside our industry; paver mfrs, contractors & suppliers must be educated in permeable systems if they are to be involved in them.

[Granite]

I agree with you about education but it's not easy finding sources. Experience is even harder to obtain. Estimating and bidding are harder than the actual work. That's why I started asking questions here - not that you can learn all there is to know on the internet but I'm hoping to at least pick up a few ideas. Thanks for your input.

[teacher]

There is a very informative class offered at the School for Advanced Segmental Paving called "Permeable Paving Systems." It is a one day seminar style course designed to familiarize students with the proper application of equipment, techniques, and materials in a permeable system. Chuck Taylor of Advanced Pavement Technologies typically teaches it, and he is probably the country's foremost expert on permeable pavements. I have taken it, and it is worth its weight in gold if you are interested in getting a leg up on all the other guys out there installing permeable incorrectly. I would highly recommend taking it if you are looking to learn more.

[windsordog]

Permeable pavers are getting bigger every year, but it is getting a bad rap because there are some rookie paver layers out there installing these systems that have no clue. And when the finished product fails the next year, customers look at it as a system that will not work. I recommend taking the coarse at the S.f.a.s.p. for permeable pavers so we can sell this on proper installs. And if the manufactuers and the landscape supply stores don't explain this better when Joe Blow wants this in his driveway or patio, that it is a system, and not your ordinary paver installation we will never get this to where it can be. Put your show on the road guys (the school) at least in the summer 1 time a month in states that are interested, and promote attending in Wis. in the winter when people are laid off or slow.:eek:

[Granite]

What are the major mistakes being made by contractors? I assume it involves the base but can you give any specific examples? Thanks.

[teacher]

Well, there are too many to name. I have seen contractors use chip for joint fill that contain a large amount of fines. Ultimately, the fines just clog up the voids between the pavers and water doesn't pass through the system. It is so important when beginning a permeable installation, or for that matter any installation, to inspect your aggregate before you use it. Just because your supplier is telling you it is washed doesn't necessarily mean that it is. Others aren't installing drainage tiles in the system when warranted, and the whole system begins to pool water, ultimately leading to a failure. Can't stress it enough how important it is to get the information on the way the whole system is constructed before attempting an installation.

[Granite]

What about base and sub-base? Installing large open graded crushed stone on a big site is not something the typical hardscape contractor is capable of doing. Is the sub-base usually installed by other site contractors? What about the base? I see problems screeding a uniform 2” bedding course if the base and sub-base are not properly graded. Or am I overreacting? Can the bedding course be used to correct for improper base course grade on a permeable system? What’s the affect on the pavement structure if the bedding course ranges from say 1” to 6” thick to compensate for the grade of the base? What tolerance is acceptable on the base course grade?

[Granite]

Is anyone involved in permeable residentail applications?

[Whyzman]

Where I live in Minnesota, one of the biggest residential permeable pavement companies subs out their excavation and base installs. Unless you have your own "big" equipment this certainly makes sense. The logistics involved with the removal, putback, and proper packing of the base are simplified. In most urban communities, for example, you're not going to be able to be dumping product onto the streets. Finding a place to dispose of a tearout (asphalt or concrete) may be a problem, as well as a suitable place to accept the excavation clean fill.

The minimum depth for a driveway by the aforementioned company is 15" (12" of base material and 3" for sand and pavers...this is for standard hollands). That's a lot of material for a double drive. The big boys are equipped to expedite and bring in equipment that'll pack your base to the necessary near concrete density.

Again, the logistics for a do it yourself excavation are mammoth. For example, if you have 10 yards of class 5 or, roadbase recycle mix brought out to a site and you're packer can only handle 2" lifts, I doubt a truck driver is going to sit by while the load is placed and packed. Dumping onto the city street may be prohibited. Or, dumping onto a finished lawn would destroy it.

The rule of thumb is that when the base is finished packed, "this is how the driveway will look." The 1" sand is only for setting, not to be used as a substitute for compacted base material.

[Whyzman]

A few more thoughts...

Bidding can be simplified if one decides to go with an excavation company for the tearout/removal and base material application. They can provide hard numbers for their aspect of the job. Some, as I mentioned above, do this regularly for permeable pavement contractors...take a look at their work...get more than one bid.

Clients will appreciate not dragging things out while you attempt to do over weeks with a skidsteer what an excavation company can do in a couple of days. They can have you finetuning the base in preparation for the pavers in record time. Remember, folks don't want their driveways torn up for any length of time...it's an inconvenience for them which will not bode well for you if things get dragged out. Installing the pavers, in my humble opinion, is the easy part and can normally move along impressively.

As some of the other folks have pointed out, there's a boat load of failed installs. It's amazing the number of failed block retaining walls just in the suburb where I live in Minneapolis. Paver driveways are not so prolific and exist pretty much in the higher end housing areas. However, there are folks willing to invest in permeable pavements in less wealthy neighborhoods who realize the beauty, longevity, and value, added to their properties. A failed install is simply not an option if one is just starting out, or for that matter if one is well established. The cost to put in a paver drive borders on the extravagant for many...imagine having to redo a failed drive out of your own pocket! That would be extravagant!

In my humble opinion, failed drives can always be avoided. I don't want to oversimplify the actual paver install, but the success of a driveway as in many trades, is in the planning and details. Let's face it, the majority of the grunt labor placing pavers on drives today are lucky to have a 6th grade education. Someone...has laid the groundwork to get to that stage.

"Selling" folks on a proper install is key! To be able to do so, one needs to be educated. Not only would it be adviseable to attend the Pave Tech school, but I would suggest also taking in the do-it-yourself paver/retaining wall classes taught by many of the local hardscape retailers. My reasoning is two-fold both centering on exposure; to the retailers, and to "your potential customers" who are attending to learn how to do this themselves... Most, I would submit, think the grass is simply removed along with an extra inch for the sand, pavers placed, and "voila" you've a patio! Homeowners have no clue of the logistics involved in a proper installation of their driveway or patio project as they are soon to find out attending one of these do-it-yourself classes.

[Granite]

Maintenance...Do permeable paver pavements need periodic cleaning? I assume they do. What proceedures are involved in cleaning a PICP?

[teacher]

There is some great information on PICP maintenance given by ICPI. David Smith (2000) states that "permeable interlocking concrete pavements can become clogged with sediment over time, therby slowing their infiltration rate and decreasing storage capacity" (p. 41). When the voids in between pavers become clogged, they need to be vacuumed out using vacuum type street cleaning equipment. Vacuuming should be done at least once or twice anually.

[Granite]

I just completed a small permeable project where I used pave edge industrial edging. I tied the edging into the pavement with grid. The grid was laid under the bedding material then wrapped over the edging and under the pavers. Has anyone else tried this method? You can see a graphic of what I'm describing at http://www.pavetech.com/paveedge/segment2.htm

[Granite]

I'd really like to hear from anyone who has installed PICP's in residential jobs or anyone who is interested in these applications. There are ways to use plastic spacers to create a permeable pavement with most any paver (6cm) and I think this has a lot of merit for residential construction. I don't see it as a good idea for other jobs but with aesthetics being so important for residential, the spacers seem like a natural choice because it allows use of an almost unlimited number of shapes, patterns & colors. Does any mfr even make a 6cm permeable paver?

[Derek]

A couple things I noticed in this conversation I would like to comment on.

I am NOT an expert by any means, but I do get my share of second hand information about permeable pavement (the aforementioned Chuck Taylor has the office directly next to mine...haha).

I know ICPI recommends recharging the permeable system once or twice a year, but I find that completely ridiculous. Some sections of a permeable system may become loaded due to mud or dumping on the surface that impacts the void structure by filling it with fine materials, and these areas can be cleaned as needed, however I have never seen a permeable system that needs to be recharged annually. In fact most of the systems we have been a part of installing have yet to be recharged. Some of them are well over 5 years old. Recommending recharging on an annual basis is inefficient and expensive (when you take the chips out you have to replace them!). I would recommend seeing how the system performs, and eliminating sources of premature clogging (such as dirt and debris runoff from landscaping, etc.) before I recommend recharging.

Although it is an interesting idea, the use of plastic spacers to create a permeable pavement would fundamentally ruin the engineered physics of a segmental paving system. In other words, you would remove all interlock, which is what makes segmental paving function properly in the first place. If this worked...stackbond and parquet patterns would be used for ease of installation. These patterns have very little interlock...and adding enough space to any pavement pattern to create void space would have even less...and be very VERY hard to keep straight lines and even spaces.
Keep in mind, permeable pavement shapes are engineered to provide maximum interlock while also creating void space for water infiltration. Some of the shapes offered have the interlock and dimensional capabilites to withstand use in HEAVY industrial applications, such as shipping terminals (think forklifts driving around with over 100,000 pounds on the tires), airports, trainyards, etc. I know this is not the field you are looking at...but more often than not, your residential customers will be more picky than the industrial owners.

[Derek]

There are several 6cm shapes available...depending on your market. With more being added every year. Some of these shapes were designed with aesthetics in mind to be pleasing to residential customers.

I am sure I can find some available in your area...

[Willox Perez]

Permeable paving is a range of materials and techniques for paving roads, parking lots and walkways that allow the movement of water and air around the paving material.These are the common types of the Permeable pavings like Porous asphalt,Porous concrete, Single-sized aggregate ,Porous turf,Open-jointed blocks are used for paving.