By

The Joy of Disruptive Things

Disruptive technology: One that displaces an established technology and shakes up the industry, or a groundbreaking product that creates a completely new industry. Examples: cellphones, personal computers and flat screens. From www.whatis.com.

Disruptive innovation: One that helps create a new market and value network, and eventually disrupts an existing market and value network (over a few years or decades), displacing an earlier technology. Examples: Uber, Wal-Mart and iTunes. From www.innosight.com.

Does the concrete paver industry have a disruptive technology? Maybe so, and it might be carbon curing. In very simple terms, carbon curing is using carbon dioxide to cure concrete instead of air. CO2 is captured into the concrete, holding some generated by cement production. This sounds good given the rising CO2 levels in the atmosphere and the broader implications for global warming, climate change, rising sea levels, etc. Fortunately, the segmental concrete pavement industry takes a smidgeon of comfort in knowing that 95 percent of CO2 emissions comes from burning fossil fuels to heat/cool buildings and from operating ships, trains, planes and automobiles.

A requirement fixed in concrete manufacturing is curing time. While concrete never stops curing, 28 days was established decades ago for curing time prior to testing for strength, absorption/density, and freeze-thaw deicer resistance. Concrete pavers often take less than 28 days to achieve the minimum 8,000 psi (55 MPa) unit compressive strength required in ASTM C936 or the minimum 7,200 psi (50 MPa) cube compressive strength in CSA A231.2. Nonetheless, significant sums of venture capital are being invested into carbon curing of concrete pavers because it presents a disruptive 24 hours for curing instead of 672.

What does a 24-hour cure time mean regarding substantive efficiency increases? Most of our readers haven’t experienced a concrete paver plant. It consists of millions of dollars of equipment and computers that mix concrete and quickly form it into a layer of 30 to 40 pavers within a steel mold. Paver production machines can’t go much faster to reduce cycle times for vibration and compaction of wet concrete within the mold. Perhaps this could be reduced to just a few seconds if the vibration of the concrete mix happens before it enters the production mold. Another option is placing more production machines in a plant (next to another or in line) such that daily throughput is quadrupled or taken higher. This implies a corresponding expansion of curing areas within a plant, meaning larger plants.

But let’s assume that the part of the plant that makes concrete units increases output that corresponds to the curing rate output now at one day instead of 7 to 28 days. That suggests factories won’t need much time or space next to them in “the yard” to store pavers. While a larger indoor space might be needed for higher production output, plants can make and ship paving units pretty much on order, even very large orders. Inventory management becomes just in time. The need for the yard next to the plant decreases, making inventory less important, and financing costs to create it diminish.

An innovative rearrangement of old commodities like cement and CO2 present a disruptive framework. The disruption from carbon curing extends to rearranging the plant and reprogramming computers that control mixing, batching and cycle times so equipment paces with faster curing and packaging times, and on multiple machines. This seems like the difference between using radar for airport air traffic control (linear sequencing) and more efficient GPS. The latter requires operational simultaneity in a four-dimensional space with new rules for aircraft spacing on approach, landing, take-off and hand-off.

The coming disruption within the paver industry could be CO2 curing with shorter curing times. This means rethinking the configuration of existing manufacturing equipment: its extent, layout and software programming. The joy of disruption doesn’t only come from the environmental benefits of CO2 curing. It potentially comes from disruptive pricing. All of this eventually could mean that segmental concrete pavement might have a future with a lower initial cost than asphalt. That disruption is pure joy.

For more information on companies that help reduce carbon emissions from concrete products, watch the following videos:

By

Grabbing Wallets

When introduced in 2014, the U.S. Green Building Council’s LEED v4 heightened awareness of environmental product declarations or EPDs. Among significant changes to the LEED Materials & Resources credit criteria, LEED v4 now bestows a modest one point for projects with at least 20 EPDs from different construction material manufacturers. Given that buildings and sites typically contain thousands of products, this seems a small requirement by LEED v4.

One intent of this credit is to raise awareness of EPDs among construction material suppliers. This requirement has led many construction materials industries to first create product category rules (PCRs) according to ISO standards. PCRs prescribe requirements for defining the impacts of manufacturing a product, as well as outline the elements of a life-cycle assessment (LCA) of environmental impacts from manufacturing. The LCA forms the basis for creating an EPD.

EPDs list environmental impacts from manufacturing a product. They have been compared to reading a nutrition label on food packaging. Rather than fat, carbohydrates, proteins and vitamins, EPDs list the following impacts: global warming potential (carbon emissions); sulfur-dioxide, ozone and smog-type air pollutants; total energy consumed; use of renewable resources; depletion of non-renewable natural resources; nutrient emissions into waterways; and fresh-water use.

A practical yardstick for measuring these impacts is typically a unit of volume or mass of the finished construction product. For segmental concrete paving units, this is a cubic yard or meter of concrete. Most impacts per cubic yard of concrete are from carbon emissions due to producing cement and from generating electricity to run a manufacturing plant. Obviously, the energy source to make cement and electricity influence carbon emissions. EPDs favor hydroelectric, nuclear, wind and solar energy with lower carbon emissions compared to coal, gas or oil-fueled sources.

Now that ASTM issued a PCR for segmental concrete pavement products, it’s up to manufacturers to conduct LCAs, then produce and publish EPDs on their products. While the market isn’t consistently or even intermittently demanding EPDs from concrete paver manufacturers, the industry is preparing for the inevitable change. California manufacturers will likely be the first with EPDs, since that state imposed a legal mandate to trim carbon emissions. To assist the education process, the ICPI Foundation for Education & Research recently developed a guidebook for manufacturers on creating LCAs and EPDs. ICPI also developed a manufacturing material and energy-use inventory spreadsheet tool for its members.

Comparing EPDs among manufacturing segmental concrete paving products, asphalt and ready-mix concrete requires nearly equivalent PCRs. The asphalt industry will weigh in when their PCR is completed late this year or next.

While LEED and other sustainability evaluation tools have taken modest steps to raise EPD awareness in the North American construction world, where are EPDs ultimately going? They will become a critical source of data that will eventually feed into evaluating environmental impacts from a product’s construction, life and disposal/reuse. This is already happening in the building design world. It’s just starting in the pavement world.

Segmental concrete paving products are in a unique position to offer lower environmental impacts by not requiring huge paving machines and concomitant fuel consumption during construction. During their life, segmental concrete pavements offer immediate reuse in-service, a significant benefit for cities. Asphalt and cast-in-place concrete do not; those materials are removed and landfilled or later recycled.

Quantifying differences among construction, lifetime and end-of-life impacts will become increasingly important to municipal transportation agencies in the coming years.

Aggregates supplies are decreasing in some regions. Asphalt isn’t cheap. Transportation agencies are expected to build, maintain and rehabilitate pavements with less money and make them last longer.

Like Europe, agencies here will eventually move toward bidding material, construction and project maintenance life-cycle assessments. Maintenance pricing and LCA bids will spawn risk assessment/financing companies. (Maintenance price bids are already happening with some ICPI members selling permeable interlocking concrete pavements.)

All of these tools will ultimately save agencies money. LCAs will grab their wallets. That will get their attention.

By

Two Worlds Together

In 2010, the Transportation and Development Institute (T&DI) of the American Society of Civil Engineers (ASCE) hosted the first national Green Streets and Highways conference. This came from a need for stormwater managers to learn more about the world of road managers and vice versa. Stormwater managers realize that roads cover about 25% of urban areas, generating significant property damage from water pollution, minor flooding and combined sewer overflows in older cities. Not surprisingly, road managers view stormwater as a lower priority compared to road user safety and efficiency. Also, road agencies generally are larger than stormwater agencies at every level of government, and that typically translates into greater financial, technical and political clout.

Most road agencies view permeable pavement as suitable for car parking lots and alleys with occasional applications in low-volume residential streets. Such projects are at the margins of road agency priorities and their budgets, and many of these applications lie in the private sector. Permeable pavements have yet to be embraced by road agencies because they are seen as new and untried under regular truck or bus traffic. This is where more structural testing and evaluation of hybrid pavements may allow for more passes from higher-weight vehicles. This can place permeable pavement more in the mainstream of the road manager’s world.

Along these lines, moving permeable pavements more into mainstream acceptance and use by road managers will require several components. As noted, first and foremost is accelerated, full-scale load testing to validate the ability to withstand truck traffic. Such testing must result in structural design methods and easy-to-use, reliable thickness charts. While there has been some full-scale load testing for pervious concrete and porous asphalt, a recent full-scale load study by UC Davis on PICP resulted in design charts. This magazine issue includes a summary of the UC Davis work, cost savings implications for designers and where the charts will be used.

The second component is specifications. Cities and county road agencies often rely on, adopt and adapt construction specifications developed by state departments of transportation (DOT). Even provisionally issued specifications by a state DOT tells local road agencies that a particular technology such as permeable pavement has been vetted by knowledgeable experts. There are currently two DOTs that have published PICP specifications; Caltrans and Washington, DC. ICPI assisted in developing these. We hope to do more of this.

The third component is training. There are two sides to the training coin: one is for contractors that results in certification of competent, experienced individuals; the other is inspection training for road agency personnel. ICPI has seen fast growth in PICP classes for contractors and in those receiving a PICP Specialist Designation. This credential is becoming a requirement in local and state agency specifications. To help address this need, an inspection presentation is now available for ICPI members to present to stormwater and road agency personnel.

The fourth component is maintenance/management procedures and costs. A critical maintenance aspect for permeable pavements is regular surface cleaning with vacuum equipment. Permeable pavement will be more readily embraced by state DOTs and especially by local road agencies when existing street cleaning equipment can be used for cleaning. Regularly maintained PICP performs for decades. However, many installations don’t see regular cleaning that results in restoration of the surface infiltration with powerful vacuum equipment and perhaps water. ICPI has funded maintenance research in the past. This includes work by North Carolina State University and the Toronto and Region Conservation Authority. ICPI and its sister organization, the ICPI Foundation for Education and Research, are reviewing more research options for the near future.

This issue’s cover story features another realm where the two worlds of stormwater and pavement are usually close together, and that’s on military bases. These mostly self-contained environments are of such a scale that one person or a small group of people down the hall from each other manage pavements and drainage. There are a growing number of them using interlocking and permeable interlocking concrete pavements. The cover story provides an example of integrating the two worlds of pavement and drainage management from a need to solve flooding problems and pavement rehabilitation.

As industry, academia and governments address the four requirements for permeable pavement that lead to it becoming mainstream road infrastructure, the two managerial worlds will work more closely together. One resource that can support this process is ASCE publishing a new book called Permeable Pavements.

By

Inspection of PICP Systems

With the rapid growth of permeable interlocking concrete pavements (PICP), there is a pressing need for increased awareness and improved execution of inspections during construction. The greatest needs often emerge in two areas: 1) pre-construction coordination among project owners/manager, designers, product suppliers, testing labs, the contractor and subcontractors; and 2) compaction inspection for PICP system stability and long–term performance.

To better address these and other needs, ICPI released a one-hour PowerPoint presentation on PICP inspection for project inspectors. The presentation also informs designers, job superintendents, crews and product suppliers about inspection aspects common to most PICP projects.

The program is approved for one hour of ASLA and AIA continuing education credit and is also eligible for earning one professional development hour. For ICPI certified installers, this program also earns one hour of continuing education for maintaining certification. For a presentation, contact an ICPI manufacturing member with a request. To find those nearby, visit the home page of http://www.icpi.org and use the “Find a local…” search engine. ICPI members providing the presentation must be ICPI-approved continuing education program presenters.

By

Essential Reading

Sponsored by the Low Impact Development Committee of the Urban Water Resources Research Council of ASCE’s Environmental and Water Resources Institute, Permeable Pavements presents a comprehensive, 260-page resource on design, construction and maintenance of permeable pavement systems. This e-book and printed edition represent a significantly updated compilation since Bruce Ferguson, FASLA, wrote Porous Pavements in 2005. ASCE’s book is richly illustrated with photos, diagrams and tables.

Permeable Pavements synthesizes diverse materials and practices using this technology with the help of academics, industry, civil and environmental engineers and scientists. The book benefits from these viewpoints with 17 authors plus 13 contributors and reviewers.

The book’s three primary editors, Bethany Eisenberg, LEED AP, Kelly Collins, PE and David R. Smith provided the structure, fact-checking, graphics and a consistent narrative style. The result is a book that can be used on almost every project.

KB ASCE ReleaseSubFeature 200x3002

The book presents an overview of design considerations common to all permeable pavement systems in the first chapter. Detailed design, construction, use and performance information follow in separate chapters on porous asphalt, pervious concrete, permeable interlocking concrete pavement, grid pavements and some recent proprietary products. Additional chapters summarize maintenance considerations, hydrologic design approaches, essential components for specification writing and key areas for additional research. The book’s extensive use of fact sheets and checklists can be instrumental in design, construction and maintenance by stormwater agencies, designers, contractors and project owners. Appendices also include a fact sheet clarifying information on common concerns, as well as tables summarizing water quality treatment performance and costs.


The downloadable e-book and soft cover print version each retail for $120 ($90 for ASCE members). Visit the “publications” section at www.asce.org to order the book.


By

Basic Draining

Arriving at the base operations building at Peterson Air Force Base in Colorado, civil engineer Fred Brooks, P.E., LEED AP, is still struck by the beauty of an intricate compass design. It’s created with multi-colored concrete pavers, arranged in a huge circle. But he’s equally thrilled by the pavers in the parking lot. “Everyone loves these pavers,” says Mr. Brooks, U.S. Air Force Environmental Element Chief, 21st Civil Engineering Squadron. “We may have started these projects on this base as a way to handle stormwater, but they’ve done much more than that. They’ve shown how attractive and welcoming a base can look.”

Peterson AFB first started considering pavers to help meet the stormwater runoff requirements established in the 2007 Energy Independence and Security Act. Section 438 mandates all federal facilities manage runoff from 95 percent of all storms. Meeting this requirement often requires permeable pavements.

In Colorado, storms can come up suddenly with short-term deluges, causing flooding. Mr. Brooks says airfields quickly became submerged and buildings flood as well. Even without Section 438’s mandate, Mr. Brooks knew something had to change. After attending a seminar in Spokane, WA, and hearing about permeable pavers, he experienced a light-bulb moment. “This was the answer we needed,” he says. “I just had to get everyone else to see the light, too.”

Invalid Displayed Gallery

GETTING BUY-IN

Mr. Brooks began by dividing the base into drainage catchments, focusing on the most problematic sections first. For example, one particular street with a catchment area of 35 acres included several older buildings that drained into the street. Flooding was a frequent concern, but a detention pond was deemed unfeasible and a complete sewer replacement would have been costly.

Mr. Brooks knew getting buy-in from others on base was crucial for such a significant project. Thus, he had the road to McDonald’s replaced with pavers. “Almost everyone on our base uses that road,” he says with a laugh. “I’m not sure if that’s good or not, but it’s the way it is. By paving that road first, I was able to expose people to the value of pavers, aesthetically and functionally.”

He also addressed weight load concerns by calling a special meeting (see sidebar) and composing a presentation about short-term versus long-term costs to assure base decision-makers that pavers were worth the investment. For instance, he noted that maintenance crews repainted road stripes nearly every year. By utilizing pavers as the striping instead, repainting costs would be eliminated.

In his presentation, Mr. Brooks emphasized how easily utilities could be accessed, as well as the advantages of more efficient road repair. He also discussed the aesthetic appeal of pavers. “Ultimately, we want people who are working here to be happy, and everyone feels better when they’re at a place that looks nice,” says Mr. Brooks.

MULTIPLE PROJECTS

After managing and shaping perceptions about cost and concerns about weight, Mr. Brooks was able to embark on a multi-stage project that involved several roads and parking lots, as well as the compass design for the entrance to the base operations building. The pavers, produced by an ICPI member, feature a minimal chamfer and smooth surface. This made them more suitable for pedestrian areas and wheelchair access and thus the design complied with the Americans with Disabilities Act design guidelines.

Mr. Brooks designed two separate permeable pavement sections for Paine St. based on flow and infiltration conditions. The first included a drainage pipe at the subgrade level below an open-graded aggregate reservoir layer. During periods of heavy runoff from storms producing flash flooding, the aggregate storage layer provides a buffer to control the discharge rate from the drainage pipe. The other section, which doesn’t require a drainage pipe, allows Mr. Brooks to assess the system’s ability to handle direct infiltration into the sandy subgrade.

The first installation involved more than 18,000 sf (1,670 m2) of pavers in a herringbone pattern, followed by another installation of the same area. In the second project, which was also a roadway, a section of the street had a low point that often flooded after storms. Although extension of storm sewer lines would have resolved flooding, that was deemed too expensive. Permeable pavers eliminated the need for storm sewers and project to outlast asphalt by a considerable amount of time.

The next phase for the base operations building included 20,000 sf (1,860 m2) of permeable pavers for the parking bays and for the compass design. The effort was so notable that the contractor, ICPI member Rocky Mountain Hardscapes, won a Hardscape North America Award in 2011 for the project. From there, two more parking lots were installed in 2012 and 2013 with more than 56,000 sf (5,200 m2) of pavers.

The permeable pavements dramatically reduced, and in many cases eliminated, the need for detention ponds for managing stormwater and snowmelt. In fact, when Mr. Brooks leads tours of the facility, he often dumps a bottle of water on the pavers to demonstrate their infiltration efficiency. Since achieving LEED credits is also important for the base, the designers were able to qualify for stormwater credits by demonstrating better control of peak flows, erosion mitigation, and increased on-site infiltration. “It’s human nature to resist change, and to look at the cheapest option,” says Mr. Brooks. “But what these projects have shown is that you can implement change in a way that’s cost-effective and appealing on a number of levels.”

FOLLOWING PETERSON’S LEAD

Peterson Air Force Base’s use of concrete pavers serves as an example to other military bases and federal facilities, especially with regard to meeting the requirements in the Energy Independence and Security Act. Like Peterson AFB, many will be searching for ways to handle runoff while implementing long-term solutions that are durable, cost-effective, and sustainable. This appears to be happening.

Mr. Brooks notes that since Peterson AFB installed the permeable pavement, the Air Force Academy installed pavers for a 58,000 sf (5,400 m2) parking lot attached to its medical clinic, and Fort Carson utilized pavers for a test pad for tanks.

Looking to the future, it’s likely that paver projects will continue at Peterson AFB, since Mr. Brooks has mandated it. He revised the base’s “facilities of excellence” plan that outlines requirements to contractors so that permeable pavers must be used on any parking lots and low-volume roads in the future. “I wanted to make sure that these efforts wouldn’t be lost when I move on,” he says. “The pavers have made such a difference on this base, and I want that to continue.”

By

Weight and See

Engineers and architects often must emphasize that concrete pavers can handle the weight of large trucks, as well as heavy traffic. But on a military base, perceptions about weight can be even more acute. For example, when it comes to a 68-ton tank that repeatedly traverses one area, some assume that pavers won’t work. They believe it is a residential-only product for patios.

When considering pavers for Peterson Air Force Base, Fred Brooks also encountered hesitation from others about weight loads, especially on well-used roads. So, he invited all the base’s operations professionals to a meeting with one of the developers of permeable pavers. “A subject matter expert stood at the front of the room and everyone just threw questions at him,” says Mr. Brooks. “They were invited to ask whatever they wanted. Voicing concerns and receiving information about weight loads went a long way toward increasing assurance about the issue,” he notes.

Because the pavers can accept high loads, other military bases began noticing the success at Peterson AFB. Recently, Fort Carson in Colorado Springs constructed a permeable paver test pad for tanks in part due to the example set by Peterson AFB. The test pad easily accommodated the weight and turning forces from one of the heaviest battle tanks in service, the 68-ton M1A1 Abrams.

Photo Caption: A paver test pad at Fort Carson withstands the load of an M1A1 Abrams tank. (Credit: Continental Hardscape Systems, LLC)

RETURN TO FEATURE STORY: “BASIC DRAINING

By

Green Alleys of St. Louis

Taking cues from the successes of projects in cities like Chicago, St. Louis has installed several green alley projects since 2007 utilizing permeable pavers and interlocking concrete pavement. The Tower Grove Heights Green Alley Paver Project was completed in two phases from 2011 to 2014. It updated 400-year-old alleys with permeable pavers through a federal Community Development Block Grant, a state Department of Natural Resources grant, and local tax-based funding. PICP was used to reduce stormwater runoff and maintain the historic appearance of the alley, originally laid in brick over clay.

In 2009, the City of St. Louis commissioned a Pilot Green Alley project using donated materials and labor. Three alleys were installed that year with pervious concrete, porous asphalt and PICP. The performance of the city-owned alleys is being evaluated over time. All of these are built over open-graded aggregate reservoirs, allowing stormwater to drain through the system per the City’s specifications.

“We helped fund a portion of them because of the experimental nature of the materials at the time,” says John Grimm, of the Metropolitan Sewer District. St. Louis also used tax funds for the $41,000 Cherokee Green Alley Concrete Project, a 150-ft long by 12-ft wide alley completed in 2009. The pilot project’s outcomes are still being tested, with MSD conducting a report on flow measurements scheduled for completion at the end of 2015.

Green alleys are not unique to St. Louis, but the city’s history and layout with centuries-old alleyways and roads lends to more paver installations in the future, Mr. Grimm says. “There are some suburbs that have alley arrangements, but they are not as prevalent,” he says. “It’s mainly particular to the city.” 

return to River City Green

By

Permeable Design Pro Upgrade

Permeable Design Pro, a software application for hydrologic and structural design of permeable interlocking concrete pavement, now features CAD drawing output (see example drawing). Drawings are generated by the program after calculating the subbase thickness for water storage and subgrade infiltration, as well as the required subbase thickness to support anticipated traffic. The program automatically selects the thicker of the two subbase solutions and presents the CAD drawing from a menu selection. The drawing can include an underdrain, geotextile, and an impermeable liner if no infiltration into the soil subgrade is desired. The CAD drawing also specifies the height of the underdrain outlet, if the designer indicates this in the program, as a means to detain some water for infiltration.

Also, the user can modify the CAD drawing by changing the subbase thickness and the underdrain pipe diameter, as well as the presence or absence of geotextile or an impermeable liner. The CAD drawing can be saved as a .dwg file for use in project drawings or submittals.

Permeable Design Pro can be downloaded from www.permeabledesignpro.com for a 30-day free trial. The purchase price is $190 per license with a discounted price of $95 for design professionals and ICPI members.

Permeable Design Pro

Permeable Design Pro software now features CAD output of design solutions for permeable interlocking concrete pavement.

By

River City Green

The Midwest is no stranger to the use of interlocking concrete and permeable pavement solutions for many private, commercial, municipal and educational projects. In particular, municipalities with rivers that overflow seasonally and those receiving polluted stormwater are increasingly deploying permeable interlocking concrete pavements (PICP) for their projects and enjoying the benefits.

In St. Louis, the challenges of an aging combined sewer system and new stormwater requirements mandated in 2006 by the City’s Metropolitan Sewer District (MSD) led to the implementation of PICP in alleys, parking lots, sidewalks, trailheads and many other applications. Multiple projects including a series of green alleys constructed since the MSD mandate demonstrated concrete pavers as a trusted solution for many City initiatives, as well as for private projects. While often used to reduce stormwater pollution, the successful performance and aesthetic appeal of concrete pavers in projects across the city has led to their popularity and continued use.

Eco-Installation: Lewis and Clark Community College – National Great Rivers Research and Education Center

At the National Great Rivers Research and Education Center at Lewis and Clark Community College in East Alton, IL, it’s all about green. Established to lead research, education and outreach related to the interconnectedness of large rivers and their communities, being “green” was non-negotiable for the center’s construction. The first of two phases of construction began in 2008 with a field center to drive research and serve as a home base for educational programs.

The project secured a total of $6.8 million in construction funding with an additional $16.3 million designated by former Illinois Governor Pat Quinn. From the project’s inception, the goal was obtaining the highest Leadership in Energy and Environmental Design (LEED) certification. LEED credit-earning components for this project include: sustainable heating and cooling systems; a detention basin for stormwater quality control; plus permeable interlocking concrete pavement, as well as other pervious pavement systems.

The paver portion of the project includes a plaza, sidewalk and main access road totaling more than 25,000 sf of manually and machine-placed pavers, installed in less than one week’s time. Speed of installation was a factor in the project’s success because it quickly opened the roadway (unlike other pavement options that require downtime while curing), thus enabling multiple construction efforts to occur simultaneously.

“The facility is a showplace for green building that incorporates multiple types of green paving systems,” says Dave Godar, P.E. for Sheppard, Morgan & Schwaab, Inc. Material reuse was accomplished by using fly ash in the cast-in-place concrete and in the modified soil road base.

Also, the project had to consider the historic flood levels from the nearby Mississippi river. “We didn’t want permeable pavement where the flood level is, because it could clog,” Mr. Godar says.

The sidewalk portion of the project covers about 875 square yards; another 2,500 square yards makes up the roadway. The system uses 3-1/8 in. thick concrete pavers, 2 in. of bedding aggregate, 4 in. of open-graded aggregate base and 12 in. of larger aggregate subbase over filter fabric or geotextile.

“There are two schools of thought about using filter fabric,” Mr. Godar says. “Some say that over time the filter fabric can become clogged and prevent the rainwater from soaking into the ground. This site had sand material as the subgrade. We opted to go with filter fabric to prevent the underlying sand material from migrating up into the voids of the subbase aggregate, which could cause settlement of the pavers.” 

To reduce labor costs, project design included machine installation for the interior pavers. “It was all kind of new,” Mr. Godar says of the plans created in 2009. “We hadn’t done anything like this before, although there were some examples out there.”

Funding for the project included some federal highway money, which meant all approvals had to go through the Illinois Department of Transportation (IDOT). Because many of the components were not standard and were not covered by IDOT specifications, some of the materials were considered experimental. The project took most of the 2010 construction season to complete. “The idea was for this to be a showplace,” Mr. Godar says. “It is open to the public, so if we had clients who wanted something similar, we could point them to the National Great Rivers Research and Education Center.”

Health Appeal: Ranken Jordan Pediatric Bridge Hospital

{gallery}2014fall-ranken-hospital{/gallery}

At Ranken Jordan Pediatric Bridge Hospital, about 15 miles northwest of St. Louis, permeable pavers satisfied the hospital’s stormwater requirements, providing an overall healthy feel to the campus. Coined a “bridge” hospital, the facility staff works to help children transition between hospital and home. With a history of expansion and growth, the hospital was built in 1941 as the Ranken-Jordan Home for Convalescent Crippled Children. In the 1960s, it expanded to accommodate more patients and staff, and in 2002, moved to a new 62,000 sf, 34-bed facility in Maryland Heights, MO. Several years later, the facility required more parking for patients and visitors.

When the organization first looked into expanding its parking capacity in 2009, stormwater requirements came into play immediately. The facility includes bio-retention basins and rain gardens. PICP met the MSD’s stormwater reduction requirements.

“At the time it was fairly cutting edge,” says Ted Spaid, co-founding principal of SWT Design, based in St. Louis, which led design for the project. “The MSD had just started enacting water quality management regulations for the region.” Rather than using underground stormwater tanks and other solutions, the design team decided on PICP to meet the requirements.

The first of Mr. Spaid’s projects with PICP took place at SWT’s office as an early test run right when the pavers first became available. Having successfully worked with them, SWT decided to use them in the hospital project. The pavers were manually installed between September and October of 2009, but required some special design attention because the parking lot presented a challenge with its radial layout. The designers addressed this by taking advantage of the paver pattern. The contractor installed the entire parking lot in a herringbone pattern, which can accommodate radial layouts, and saw cut the edge pavers to fit the non-uniform shape.

Another unique design element used pavers in contrasting colors to designate parking stalls rather than paint lines on the pavement. “The installation itself was a month-long process,” Mr. Spaid says. But the outcome was several-fold, for the 20,980-sf installation. First, it satisfied required municipal green elements by draining to rain gardens to help with bio-filtration. And while there was additional expense due to the paving materials, the aesthetic appeal was a positive payback.

“Many clients are timid about wanting to spend the extra money on permeable pavers, but then they realize it delivers more than stormwater management. If you can turn stormwater management into a positive aesthetic attribute, it’s much nicer. There are multiple layers of savings by using the pavers correctly and strategically.”

For example, the parking lot design allowed for surface runoff to sheet-flow over the asphalt and infiltrate into the permeable pavers. Eventually, that water would go to a centrally located rain garden or bio-retention area, and would flow to a larger detention basin as needed to prevent downstream flooding.

“This design replaced the need for typical drainage structures and piping system that you would find throughout a parking lot,” Mr. Spaid says. “Based on a cost-benefit analysis, a traditional stormwater infrastructure design was comparable to the cost of the permeable paving system. Furthermore, the permeable pavers provided the required stormwater management to decrease the flow of runoff and help control sediment.”

The pavers and rain garden also decreased the size of the necessary detention basin and preserved land for future expansion. The project is maintained with annual vacuuming and regular cleaning. MSD requires an annual inspection report that includes dates of inspections and cleaning methodology. Additionally, the report must confirm that all stormwater structures are functioning and that watersheds have not been disrupted by pavement clogging or erosion. The report must demonstrate that all best management practices (BMPs) and landscapes are functioning as designed.

In a care setting, particularly one focused on children, the sub-story is aligning construction materials with quality and health, Mr. Spaid says. “It’s a healthy living story,” he says. “Here we are at a pediatric care facility and we want to show quality care for children. Through stormwater management and rain gardens, there’s a story to be told about water quality and creating an environment not only contributing to a healthy planet, but to human well-being and aesthetics.”

Trailhead Series: Great Rivers Greenways

{gallery}2014fall-GRG-trails{/gallery}

Concrete pavers may be “green,” but they’re not often found in the woods. The Great Rivers Greenway (GRG) District is an exception. The network spans more than 100 miles of trails and greenways among 1,400 acres through St. Louis City, St. Louis County and St. Charles County that support hiking, biking, walking and other outdoor activities. Established in 2000, the GRG initiative set out to improve health, reduce pollution and stabilize communities, among its many goals.

That’s where PICP comes in. In 2006, the organization extended one of its trails, which involved installing two new trailheads. Given the stormwater restrictions then recently passed by the MSD, the Great Rivers Greenway project managers and designers crafted a proposal for PICP as the surface for the new sites. A handful of other trailheads and parking areas built in the following years also realized the benefits from PICP.

“We considered leaving it asphalt,” recalls Carey Bundy, project manager for GRG. “It would be cheaper on the front end,” she says, “but PICP would count toward water quality credits. We went with pavers mainly because if something did go wrong later, they are much easier to get into and work on.”

Because it spans the city and two counties, funding for GRG projects comes from various sources, including tax dollars and federal grants. GRG resources are used to build and improve the trail network and then projects are turned over to the municipalities for maintenance. Working with pavers required a lot of testing, partnerships on design elements and determining performance requirements that would satisfy the mission of the trails.

The installations were not easy. “The most challenging part is the location and site accessibility,” says Scott Rozier, president of St. Louis-based Rosch Company. “The trails go through the middle of the woods, or across old abandoned tracks, and it’s very challenging logistically to get the subbase installed and place everything where it needs to be.”

In spite of the challenges, GRG found that the PICP systems with additional green elements such as plantable walls and reclaimed water systems have performed well. So well in fact, more projects are in the design and planning stages as a result. “Initially, people said they wanted to go with the traditional route and didn’t want to try this new but different material,” Ms. Bundy says. “But it’s on the ground now in a lot of places. Getting a pilot installed so people can see what it is, that is very helpful.”