Application of Porous Pavement

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Application of Porous Pavement
A Water Balance Perspective

• May 12, 2006
• Richard Boase, P.Geo., CCEP
• North Vancouver District

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Why Change at All

• Why is this an issue?
• How do we implement effective change?
• How do we monitor results of decisions
  made?

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What's the BIG deal?
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Single Family Rainwater Mgt.

• DNV encompasses 16,237 Ha. (63 mi.2)
• 64.5 Wilderness Area
• 19.5 Residential
• 8.3 Urban Parks
• 3.3 Conservation
• 2.1 Industrial

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Single Family Rainwater Mgt.

• Population approximately 80,000
• 27,319 dwelling units (incl. M/F)
• 70 detached single family
• 11 increase in dwelling units 1986-1991

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Single Family Rainwater Mgt.
Science tells us that watershed health begins to
deteriorate as a watershed moves beyond 10 total
impervious surface area.
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Total lot area 1901 sq. m.
Aging SFD stock gt50 years Lower land
value Different appreciation for space
15 Landscaping
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Total lot area 1972 sq. m.
28 Landscaping
New SFD stock lt 10 years Higher land
value Different appreciation for space
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59 increase
88 increase
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Single Family Rainwater Mgt.
How do we implement change?
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Single Family Rainwater Mgt.
2005 Rain Data (mm)
We need a new approach
Over 80 of rain small frequent showers lt than
50 mm
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Single Family Rainwater Mgt.
Site
Building size Hard surface Landscaping
Watershed Health
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Single Family Rainwater Mgt.

• Yes we can make a difference if we have
• Policies
• Bylaws
• Standards for greener designs

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Pervious Paving

• We needed something to give us a nudge

Who would ever have thought it would come from a
simple Council discussion over a routine lane
paving project!
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Pervious Paving

• Open Graded Asphalt

• Hot mix asphalt with inter-connecting voids
• Developed as a highway safety feature to reduce
  hydroplaning, skidding and tire noise

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Pervious Paving

• Could we adapt an existing use of open graded
  asphalt?

• Used as a tennis court surface
• Well draining
• More use year round

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Pervious Paving
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Pervious Paving

• Geotechnical Assessment First

• Variable permeability rates (50 -135 mm/hr)
• High fines content (18 45 )
• Organic content under existing lane surface

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Pervious Paving

• Geotechnical Assessment First

• Flat topography
• No ability to raise grade
• Concern about capillary action fines

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Pervious Paving

• No alternative but to excavate and install a
  suitable sub base layer

• 300 mm thick base course
• 25 mm gravels with lt 5 fines (75µm)
• 75 mm layer open graded asphalt

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The End