PERMEABLE
PAVEMENT SEMINAR
| Discover
Why Permeable Pavements Offer Clear-Cut Investment Value!” |
| PERMEABLE
SYSTEM |
 |
| The system requires a 12-in. – 24-in.
deep sub-base of stones (depth requirements vary according
to the size and type of application), a 4-in. deep base of
1/4 in. – 1 1/2-in. clean gravel, and a 2-in. bedding
of 1/8 in. – 1/2 in. grits. |
| “A
Best Management Practice (BMP)” |
 |
| To assure efficient water runoff, the
developer chose a permeable pavement using Cambridge Cobble
III from the Excalibur Collection on all entrance roads and
driveways in this waterfront townhouse community. After four
years, the system is performing well. |
At Cambridge, we recognize that the permeable pavement system is
becoming a hot topic in the segmental paving market. To get a handle
on the latest results of this alternative pavement, I attended the
Permeable Paving Seminar at the new School for Advanced Segmental
Paving in Franksville, Wisconsin in September. I am pleased to provide
a very positive report — filled with somewhat surprising advantages
and statistics.
Chuck Taylor from Advanced Pavement Technology, a specialist in
permeable systems, explained the benefits of using this type of
system for stormwater management to a full classroom mixed with
manufacturers, contractors and others interested in the latest information
on permeable pavements.
Mr. Taylor reaffirmed that although urban development is often a
sign of progress, it also contributes pollution to our environment
through excessive stormwater runoff. When stormwater or melting
snow runs over impervious surfaces, it becomes a form of non-point
source pollution with the potential to damage local water quality
and harm aquatic life in streams that flow through urban areas.
Because of this potential environmental threat, developers frequently
find that under the Clean Water Act, their sites are exposed to
the latest federal regulations. Obviously, they must comply with
the regulatory requirements for stormwater management. Until recently,
compliance usually meant dedicating precious and valuable real estate
for a retention pond.
A Simple Solution For A Complex Problem
Open-minded owners and developers are turning to permeable pavements
to support stormwater management and thereby eliminate the need
for space-wasting retention ponds. The system allows for natural
stormwater drainage and groundwater recharge, making it ecologically
and economically sound. The permeable components allow water to
flow through and retaining water to runoff directly through a series
of natural filtration systems before it enters nearby streams or
rivers (see diagram). An acceptable structural Best Management Practice
(BMP), this method meets the federal stormwater management requirements.
By using it to comply with these regulations, owners and developers
can also earn LEED (Leadership in Energy in Environmental Design)
credits from the United States Green Building Council.
With a permeable pavement, owners and developers opt for a superior
interlocking pavement surface while making more efficient use of
real estate otherwise slated for retention ponds. Properly installed
permeable pavements outperform other systems in harsh climates with
freeze/thaw cycles. In addition, these systems and components can
withstand vehicular traffic. Combining all of these factors, projects
consistently show outstanding results on a 30-year lifecycle cost
analysis. Add in its unique curb appeal along with convenient access
for maintenance and you will discover why permeable pavements also
offer clear-cut investment value and solid business benefits.
How Much Stormwater Can These Systems Absorb?
The co-efficient of run-off for permeable pavements at dead flat
has been proven to be .15 where asphalt is .98. A minimum 1% grade
is recommended so that the c value becomes .25. The design value
should be at .40. A 100% breakdown of first-flush pollutants in
the bacteria system takes 5 years to complete. At this point, the
system will continue to absorb a 2.5” storm event. The void
ratio in the sub-base aggregate is 40% and there is still another
9” of system left to store run-off from rainstorms.
Cambridge Cobble III: A Permeable Pavement Solution
This 8-sided shape is typically used in conjunction with Cambridge
4 x 4 to form a pattern. When used over a filtration system, voids
left by omitting the 4 x 4 paver in the laying pattern are filled
with 3/8 in. coarse gravel allowing water to filter through the
openings and joints. Aligning the 4-in. sides together or using
a running bond pattern creates smaller 1 5/8 in. openings. Contrary
to common belief, the perviousness and amount of infiltration are
dependent on the infiltration rates of the joint filling material,
bedding sand and base material not the percentage of open surface
area.
Economical Benefits:
• Enhanced land planning through the potential elimination
of required retention/detention ponds
• Significant savings by reducing or eliminating conventional
storm sewers and catch basins
• Reduced maintenance costs for pavement repair, sealing and
replacement
• Minimized stormwater hook-up fees
• Decreased liability to owners through the elimination of
open wet areas
Environmental Benefits:
• Superior control of short-duration stormwater runoff (to
near 100%)
• Reduced downstream flows and minimized potential for bank
erosion
• Critical improvement of water quality using natural filtration
methodology
• Valuable cooling effect during first runoff capture
• Flexible capacity for detaining water under road or parking
surface
Contact a Cambridge Sales Specialist for more information
on permeable pavement solutions and the GreenSpec installation process.
(top)
By Charles H. Gamarekian
As
you know, Cambridge Pavingstones have the “ArmorTec Advantage”
— a message of added value that has continued to boost our
brand awareness over the last decade. I am reminded that complacency
can erode our branding program. With this in mind, I urge our Authorized
Cambridge Distributors and their contractor customers to continue
to advocate the Cambridge ArmorTec message. 
Generally
speaking, manufacturing a product of the highest quality requires
greater expense not too mention that most companies are experiencing
increases in labor, fuel, energy and insurance costs. And Cambridge
Pavingstones with ArmorTec are no exception. In addition, more capital
investment in equipment is necessary as is a higher caliber of operators
to make pavers of ArmorTec quality. Our overall material and fixed
operational costs are also greater and production rates are slower.
In spite of this, Cambridge Pavingstones with ArmorTec remain extremely
competitive when compared to all other brands — even those
alleged as being a premium grade.
